Looks like another terrorist is down.
http://www.guardian.co.uk/world/2005/nov/16/israel2?CMP=twt_gu
From the watchtower "It's a little girl. She's running defensively eastward."
From the operations room "Are we talking about a girl under the age of 10?"
Watchtower "A girl about 10, she's behind the embankment, scared to death."
Watchtower "I think that one of the positions took her out."
Captain R "I and another soldier ... are going in a little nearer, forward, to confirm the kill ... Receive a situation report. We fired and killed her ... I also confirmed the kill. Over."
Monday, August 30, 2010
How to make a sniper rifle. Table of contents.
Part 1: Introduction
http://1-800-magic.blogspot.com/2010/08/how-to-make-sniper-rifle.html
Part 2: Buying a Mosin Nagant
http://1-800-magic.blogspot.com/2010/08/how-to-make-sniper-rifle-part-2-buying.html
Part 3: Cleaning a Mosin Nagant
http://1-800-magic.blogspot.com/2010/08/how-to-make-sniper-rifle-part-3.html
Part 4: Disassembling a Mosin Nagant
http://1-800-magic.blogspot.com/2010/08/how-to-make-sniper-rifle-part-4.html
Part 5: Accurizing a Mosin Nagant
http://1-800-magic.blogspot.com/2010/08/how-to-make-sniper-rifle-part-5.html
Part 6: Selecting a scope mount
http://1-800-magic.blogspot.com/2010/08/how-to-make-sniper-rifle-part-6.html
Part 7: Mounting a side rail on the Mosin Nagant
http://1-800-magic.blogspot.com/2010/08/how-to-make-sniper-rifle-part-7-scope.html
http://1-800-magic.blogspot.com/2010/08/how-to-make-sniper-rifle.html
Part 2: Buying a Mosin Nagant
http://1-800-magic.blogspot.com/2010/08/how-to-make-sniper-rifle-part-2-buying.html
Part 3: Cleaning a Mosin Nagant
http://1-800-magic.blogspot.com/2010/08/how-to-make-sniper-rifle-part-3.html
Part 4: Disassembling a Mosin Nagant
http://1-800-magic.blogspot.com/2010/08/how-to-make-sniper-rifle-part-4.html
Part 5: Accurizing a Mosin Nagant
http://1-800-magic.blogspot.com/2010/08/how-to-make-sniper-rifle-part-5.html
Part 6: Selecting a scope mount
http://1-800-magic.blogspot.com/2010/08/how-to-make-sniper-rifle-part-6.html
Part 7: Mounting a side rail on the Mosin Nagant
http://1-800-magic.blogspot.com/2010/08/how-to-make-sniper-rifle-part-7-scope.html
Friday, August 27, 2010
How to make a sniper rifle. Part 7: Mounting a side rail on the Mosin Nagant
[This is the last part of the series. Table of contents: http://1-800-magic.blogspot.com/2010/08/how-to-make-sniper-rifle-table-of.html]
As described in the previous post, the best - and the priciest, and the hardest to install - scope mount is the Dragunov side rail.
This post describes how to install it.
Preserving the original rifle
Most Mosin Nagant rifles made during WWII in Russia have no historical value. Majority were rebuilt in Russian arsenals after the war from a smorgasbord of non-matching parts, sealed in cosmoline, and put away. You can safely treat these rifles as a LEGO set - it is OK to permanently modify it.
And modified it will be - the stock will have to be dremeled to create an opening for the side rail, and the bolt handle will be replaced.
If, however, your rifle has matching numbers (especially if bayonet number matches as well!), have been made before the war, and is in excellent shape, you might want to buy extra parts instead of modifying the originals. Preserving original stock and bolt body would allow you to restore your rifle to its exact original shape easily.
Note: I think modifying a pre-revolutionary Mosin Nagants in any way, shape, or form is an act of pure barbarism. There are not so many of them left! If you are a lucky owner of a pre-1917 rifle, and want one with the scope, please let me know and I will be happy to trade a finished one - with the rail installed, and bolt bent - for it. Or two unfinished ones :-).
If you want to preserve the original parts, you will need to procure the parts you will modify - the stock and the bolt body - separately. The stock is easy to buy, for example, http://www.buymilsurp.com/ has a whole lot of them in various conditions. Since you can reuse the metallic part, you will have to refinish the stock (see below), and you do not need the handguard (it only makes the rifle less accurate), you can buy a cheaper part. For example, as of this writing, there were plenty of very acceptable variants in the $25 range.
On the other hand, procuring the bolt body is very, very hard. You only need the bolt body, not the entire bolt. In fact, because you probably do not have a headspace gauge, you will need to reuse the rest of the components of the original bolt because it matches the rifle (to learn more about headspace, and what can go wrong if you don't pay attention to it, read this: http://www.surplusrifle.com/shooting/headspace/index.asp).
Bolt body is the part to which the handle is attached.
There currently is not a good place where bolts or bolt bodies can be purchased. The cheapest, but an unreliable source is your local gun show - there typically would be a few available for $10-$12. Unless you are in Seattle area, because I bought up every one that was available locally :-).
An unknown type of the already bent bolt body is sold here: http://www.tngunparts.com/m9130.htm. See below (in the Bolt Body section) for precaution - the bolt handle needs to be replaced, not just bent.
Failing that, look for ads for surplus rifle parts in Shotgun News, there usually is a place or two where you can get complete bolts for $25-$40 a piece. I bought quite a few there.
Check http://www.ebay.com/ or http://www.auctionarms.com/, the parts occasionally show up there.
Boltman (http://www.mosinnagant.net/Boltman/Boltman.html) sometimes has them in stock, but more often he does not. If he does, the price quoted on the page above ($55 for the whole thing) is very, very attractive.
Failing all that, you can buy a rifle in a very poor shape and cannibalize it. If you have a C&R license, you can often find them on the Internet for less than $40.
Failing everything else, the bolt bodies can be purchased for $34 from Numrich store at http://www.gunpartscorp.com/catalog/Products.aspx?catid=3258. Yes, this is ridiculous considering that the price of a gun was ~$100.
Remember the headspace, however - do not move the entire bolt from rifle to rifle!
Project inventory
You will need the following things for the project.
(1) The rail from http://www.kalinkaoptics.com/. $25 plus a ridiculous shipping price. Tough luck: this is the only place where this particular component can be found. On their web site, Browse Category -> Firearm Accessories -> Side Rails (http://www.kalinkaoptics.com/firearm-accessories/side-rails.html).
Be careful not to buy the undrilled side rail for $15 - it is too thin and will not stick enough to protrude above the stock surface.
(2) "Original BP-02 SVD, PSL, Tigr Low Profile Centered Side Mount to Weaver Rail" from http://www.kalinkaoptics.com/, $53 (plus the above "arm and leg" for shipping. Combine with (1) and it will be slightly less offensive). "Low profile" part is very important. This can be found in Browse Category -> Mounts -> SVD, Tigr, Romak-3 (http://www.kalinkaoptics.com/mounts/svd-psl-tigr-romak-3.html).
(3) Stock that you will feel OK modifying (see "Preserving the original rifle" above).
(4) Bolt body that you will feel OK modifying (see "Preserving the original rifle" above).
(5) Drill bit #11, drill bit #21, 10-32 tap, T-wrench to hold the tap, and 2 10-32 x 1/2" screws. This is available in the local hardware store (for example, ACE). Get the ones that are the best quality, designed for hardened steel.
(6) Cutting oil. This is a bit hard to find, but I tracked it down in Lowe's and in ACE. Home Depot does not have it.
(7) Drill press. Local hardware store, $120-$180.
(8) Drill press vise. Home Depot, $16. A few large matching bolts, nuts, and washers to fix it to the drill press table, same source.
(9) Small bulls eye level. Home Depot.
(10) Paint stripper, for example, Citristrip (http://citristrip.com/). Sand paper (coarse and fine), steel wool (fine). Two brushes. Gloves, paper towels, 2 wood blocks, old newspapers. Local hardware store.
(11) Wood stain of your choice. You should defer picking the color until you have stripped the stock of its current paint.
(12) A rotary tool like Dremel.
(13) A gun vise or an inexpensive shooting rest. http://www.midwayusa.com/, $20-$60, depending on whether you want to have something you can use for shooting, or just mounting the gun for cleaning and scope alignment.
(14) A laser boresighter. http://www.midwayusa.com/. There is no picture here because I really cannot recommend any particular model - the choice is between an expensive and crappy one ($150 LaserLyte Kryptonyte Green Laser Boresighter 22 to 75 Caliber), and a less expensive but equally crappy one ($30 Sightmark Laser Bore Sight 243, 308 Winchester, 260, 7mm-08 Remington). Price/performance of the Sightmark is better. The above-referenced caliber (243) works for 7.62x54r, although the bolt does not close. This is OK, the bolt does not close in 308 rifles either.
Bolt body
To work with any scope mount other than the scout mount, the bolt handle needs to be turned down. This is because when the bolt is open, it's handle sticks upwards and interferes with the scope. There are several ways this can be accomplished. First, there is an ATI bolt handle kit that costs around $20 on eBay and contains the replacement handle, the drill bit, the tap, and the screw. The result does not look amazing, and requires notching the stock because the handle extends directly down when the bolt is closed.
The picture below looks nicer than the reality.
As of this writing, a bolt body with the handle turned down can be bought from here: http://www.tngunparts.com/m9130.htm for $54. I have not used them, so I do not know how exactly is the bent handle manufactured,. Sometimes they simply bend the handle down without adding to the length of it. The result is not that good, there simply is not enough handle to grab it when opening and closing the action:
(the part above is available here, http://www.gunpartscorp.com/catalog/Detail.aspx?pid=291700&catid=3258 for $34)
eBay has a number of people sell bolt bending as a service: you mail them your body, they modify the handle for you, and mail it back. I used Marvin Burrows (eBay: mellbee) several times, and he does excellent job for around $46, including shipping. This is his eBay ad:
And this is the result:
The turnaround time is about 2 weeks including the mailing time.
If you are really adventurous, you can try doing it yourself using the instructions here: http://www.gswagner.com/mosin-nagant/bolt/mnbolt.html
...or here:
http://www.opticstalk.com/topic12364.html.
Side Rail
This is the "mechanical" part of the project. You will need to drill and tap 2 holes in the receiver to attach the side rail.
To do this, you need to attach the side rail to the receiver temporarily to drill the very first hole. It goes on the left part of the receiver so that its top is close to flush with the opening in the action.
This time I suggest you remove the trigger group by unscrewing the single screw that holds it on the receiver. Mounting the receiver in the vise is hard as it is, without extra parts sticking out.
Before you mount the receiver, ensure that the drill table is horizontal by using a level. You will need this to align the receiver surface to be perfectly horizontal afterwards.
Place the rail in the side of the receiver. I do not know if there is "the" right spot. The receiver is curved, and on all 3 rifles on which I put the side rail the scope ended up pointing up and to the left relative to the barrel axis. This is OK: the problem will be corrected by shimming the mounting bracket. See the couple of pictures above for approximately right location.
The legs on the rail should obviously hug the receiver and not hang out through the action's opening.
Fix the side rail in place. You can use either a very small clamp, or wrap it tightly using electrical or duct tape. Make sure that neither cover the opening which you will drill.
Plug the chamber with a tight wad of paper towel to ensure that the metallic debris from drilling does not end up in the chamber or the barrel.
Place the drill table vise on the drill table. Do not yet attach it with the bolts. Place the receiver on the vise, tighten the vise as little as necessary so that the receiver does not slide. Guide the system so that the hole in the side rail is approximately below the drill's chuck, and at the same time all four of the mounting openings in the vise intersect with the mounting openings on the drill table.
Adjust the drill table to a height where the drill bit can be lowered sufficiently to drill through the receiver.
Put the bolts through the mounting holes. Use the washers on both sides, and screw them down so that the whole system can move about with some friction. Now place the bulls eye level on the side rail, reopen the vise jaws just a little bit so that receiver can be reoriented, and move it slightly so that the bubble of air in the level is right in the center. Reclose the vise jaws and tighten them, while monitoring the bubble - when jaws are closed the receiver might shift and the leveling action will have to be repeated.
Now that the system is aligned horizontally, put the larger drill bit in the chuck. Tighten. Do not turn the drill on yet, but lower the chuck to see where it would touch the metal. By moving the vise slightly ensure that the drill bit goes exactly through the hole in the side rail. The larger drill bit should fit tightly through that hole. When it's in, rotate it around to make sure that the system is perfectly aligned and the drill bit does not scrape the metal of the side rail.
Tighten the bolts that fix the vise on the drill table. Lower the chuck again to make sure the position did not shift. Rotate it around again.
Put the eye protection on, turn on the drill and lower the larger bit just enough to make a small crater, just the diameter of the drill but not deeper than necessary, on the steel of the receiver. Raise the chuck and replace the drill bit with the smaller one. Lower the chuck to ensure that the system is still aligned. The drill bit should touch the metal right in the middle of the crater left by the bigger drill.
If the drill has an adjustable RPM, set it to medium low (800-1200). Place a drop of the cutting oil on the receiver where it will be drilled. Note that cutting oils are toxic, do not let it anywhere near your exposed skin. Use gloves!
Drill slowly, raising the chuck to clear the metal debris out of the hole often. Do not apply a force that is more than 20lb (100N). This is very important, or the drill bit can break and stick in the hole, and it might be impossible to remove it! When the hole is drilled though, remove the receiver from the vise, and remove the side rail from the receiver. Using paper towel (and gloves!) clean all metal debris from the receiver.
Put another drop of cutting oil (gloves!) on the tap. Rotate it and guide it in the hole, maintaining perpendicular angle to the receiver. Go lightly, reversing the direction, cleaning the debris and reoiling frequently. A broken tap is a disaster - it is made of a hard alloy and if broken is next to impossible to remove.
When the thread is cut (the widest part of the tap is through the hole), remove the tap, clean the receiver and the new thread using paper towels. You can now screw the side rail to the receiver using the newly made hole and one of the screws, and repeat the process for the next hope.
Useful hint: when tapping the second hole, keep the side rail in place (but clean the drilling debris out!), it will help guide the tap.
Stock
This is the last part of the project. Now that we have a rail on the side of the receiver, the stock will not fit and a cut out needs to be made to accommodate the part that is sticking out. Also, the height of the side rail is somewhat smaller than the thickness of the stock, so a small layer of wood needs to be removed from the left side of the stock so that the rail is exposed enough.
Because quite a bit of finish will be removed to accommodate the rail, we will need to refinish the stock. If you have done this before, just go with what you know, not what I write here. I am a complete novice to wood finishing, and the results I personally achieved are functional, but not beautiful.
First, use the paint remover to get the current finish off. You will need a brush, a paint stripper, steel wool and sand paper for this.
Citristrip is a paint stripper that can be used indoors, other must be used outside. Make sure that the weather is right! Vast majority of them are health hazard so be cautious and read the instructions before starting. I found that a combination of Citristrip followed by the classic stain remover works well.
Although most of the paint/wax/whatever it is will come off, some coloring will still remain.
You can probably get closer to clean wood by sanding it off with sandpaper.
After you got as much previous stain off as you think is practical, pick the stain that will (1) survive outdoors, and (2) will either match the previous stain closely or be dark enough to cover the remaining traces of the older stain. I chose the later route, so that's what you see in the pictures.
Place the barrel in the receiver and mark the places where the stock interferes with the side rail. Using the rotary tool and the sanding band...
...remove the side of the stock about 1/2 of the width of the rail. Use the cutting attachment...
...to take care of the corners. Replace the receiver to see how much the opening needs to be deepened. Keep doing this until the screwed down receiver can go into the stock all the way and the side rail still does not touch the stock.
Now take the scope or the mounting bracket and try to slide it onto the rail. You will see that the side of the stock prevents it from engaging. Again, using the rotary tool keep removing thin layers of the side until the scope mount can slide onto the rail.
Take a look at the picture below and note the depression cut out on the stock to accommodate the externalities of the scope mount.
After the barreled receiver fits (do not forget to screw it in and tighten the screws before ensuring that the rail does not touch the stock), and the scope mounting bracket fits on the rail, you are ready to apply the stain to the stock.
Disassemble the rifle back. Using the instructions for your stain and working in an open space (the fumes are toxic!), apply a coat of stain, let it dry, then repeat twice, applying the total of 3 layers.
After the stain dries completely (this will take a day), reassemble the rifle fully.
Adjusting the scope mount
As I said above, the side rail will not be precisely aligned with the barrel axis. In all my mounts "out of the box" the scope will point high and to the left. This misalignment may or may not be correctable by the scope's internal adjustment mechanism, but it is much better to instead adjust the scope mount so that the scope's natural axis is in alignment with the barrel.
There are a few reasons for aligning the mount instead of adjusting the scope.
First, the mount is probably pointing high. Even if you can adjust the elevation on the scope, your scope will be close to out of the adjustment range pointing down. So when you would want to move it down for shooting at 200/300 meters, it is very likely that you will not be able to do it because scope's adjustment range will already have been used to compensate for the rail.
Second, scopes near the edge of their adjustment ranges tend to not keep zero as well as they do when they are centered.
Adjusting the Dragunov-type mount is actually very easy. The bracket's top rail is attached to the middle part by two screws, and the middle part attaches to the part that goes on the side rail with 4 screws. The windage (horizontal) adjustment is achieved by putting shims between the middle and the bottom part, and the vertical adjustment is achieved by shimming the rail.
I use aluminum strips from soda cans for shims - they can be stacked to achieve exactly the necessary thickness.
Attach the scope to the mount. Ensure that the scope's optical axis is centered. To do this, loosen the scope in the rings and rotate it while observing the cross hairs through the eyepiece. If the scope axis is centered, the impact point will be the same while the scope rotates. Use windage and elevation adjustments to center the scope. When the scope is centered, tighten the rings.
Turn the laser boresighter on and put it into the chamber. Put the gun in a vise and point it to the wall some distance away (10 meters or more, depending on the minimum distance at which your scope still focuses). Note where the scope's cross hairs are, relative to the laser beam.
Turn the boresighter off. You will need to make several measurements, and the batteries are only good for minutes (despite what the instructions claim).
Disassemble the scope mount, and measure the sizes of the holes and distances between them.
Cut off several rectangular pieces of aluminum foil from the side of a soda can. Initially make them much larger than is really needed. For the top shims you will need to drill one big and one very small hole next to each other. For the bottom shim, you will need two holes of the same size. The drill press will help here.
It is easier to drill the holes when multiple layers of the aluminum are bunched together. After the holes are done (plan to waste a few pieces to practice) you can cut around them to size.
Add a few shim pieces, reassemble the mount and replace the scope. Turn the laser boresighter on and observe the new impact point.
The goal is to have the cross hairs about 1"-1.5" ABOVE the laser mark at 10 meters. The actual scope axis is about 2" above the barrel axis, but you want to make the centered scope point a little bit DOWN so that it does not run out of DOWNWARD alignment when shooting at distances beyond 100 meters (to track the bullet trajectory the scope gets turned down as the target is farther away).
You will have to do a few passes to get the scope almost right. It does not have to be completely on target - the last final touches are worked out using the scope's internal adjustment mechanisms. Do not spend too much time on it until you get to the range though - the accuracy of the laser boresighter is only within 10" at a 100 meters, if even that. It will get you on paper and you will use the scope's controls to get on target from there.
As described in the previous post, the best - and the priciest, and the hardest to install - scope mount is the Dragunov side rail.
This post describes how to install it.
Preserving the original rifle
Most Mosin Nagant rifles made during WWII in Russia have no historical value. Majority were rebuilt in Russian arsenals after the war from a smorgasbord of non-matching parts, sealed in cosmoline, and put away. You can safely treat these rifles as a LEGO set - it is OK to permanently modify it.
And modified it will be - the stock will have to be dremeled to create an opening for the side rail, and the bolt handle will be replaced.
If, however, your rifle has matching numbers (especially if bayonet number matches as well!), have been made before the war, and is in excellent shape, you might want to buy extra parts instead of modifying the originals. Preserving original stock and bolt body would allow you to restore your rifle to its exact original shape easily.
Note: I think modifying a pre-revolutionary Mosin Nagants in any way, shape, or form is an act of pure barbarism. There are not so many of them left! If you are a lucky owner of a pre-1917 rifle, and want one with the scope, please let me know and I will be happy to trade a finished one - with the rail installed, and bolt bent - for it. Or two unfinished ones :-).
If you want to preserve the original parts, you will need to procure the parts you will modify - the stock and the bolt body - separately. The stock is easy to buy, for example, http://www.buymilsurp.com/ has a whole lot of them in various conditions. Since you can reuse the metallic part, you will have to refinish the stock (see below), and you do not need the handguard (it only makes the rifle less accurate), you can buy a cheaper part. For example, as of this writing, there were plenty of very acceptable variants in the $25 range.
On the other hand, procuring the bolt body is very, very hard. You only need the bolt body, not the entire bolt. In fact, because you probably do not have a headspace gauge, you will need to reuse the rest of the components of the original bolt because it matches the rifle (to learn more about headspace, and what can go wrong if you don't pay attention to it, read this: http://www.surplusrifle.com/shooting/headspace/index.asp).
Bolt body is the part to which the handle is attached.
There currently is not a good place where bolts or bolt bodies can be purchased. The cheapest, but an unreliable source is your local gun show - there typically would be a few available for $10-$12. Unless you are in Seattle area, because I bought up every one that was available locally :-).
An unknown type of the already bent bolt body is sold here: http://www.tngunparts.com/m9130.htm. See below (in the Bolt Body section) for precaution - the bolt handle needs to be replaced, not just bent.
Failing that, look for ads for surplus rifle parts in Shotgun News, there usually is a place or two where you can get complete bolts for $25-$40 a piece. I bought quite a few there.
Check http://www.ebay.com/ or http://www.auctionarms.com/, the parts occasionally show up there.
Boltman (http://www.mosinnagant.net/Boltman/Boltman.html) sometimes has them in stock, but more often he does not. If he does, the price quoted on the page above ($55 for the whole thing) is very, very attractive.
Failing all that, you can buy a rifle in a very poor shape and cannibalize it. If you have a C&R license, you can often find them on the Internet for less than $40.
Failing everything else, the bolt bodies can be purchased for $34 from Numrich store at http://www.gunpartscorp.com/catalog/Products.aspx?catid=3258. Yes, this is ridiculous considering that the price of a gun was ~$100.
Remember the headspace, however - do not move the entire bolt from rifle to rifle!
Project inventory
You will need the following things for the project.
(1) The rail from http://www.kalinkaoptics.com/. $25 plus a ridiculous shipping price. Tough luck: this is the only place where this particular component can be found. On their web site, Browse Category -> Firearm Accessories -> Side Rails (http://www.kalinkaoptics.com/firearm-accessories/side-rails.html).
Be careful not to buy the undrilled side rail for $15 - it is too thin and will not stick enough to protrude above the stock surface.
(2) "Original BP-02 SVD, PSL, Tigr Low Profile Centered Side Mount to Weaver Rail" from http://www.kalinkaoptics.com/, $53 (plus the above "arm and leg" for shipping. Combine with (1) and it will be slightly less offensive). "Low profile" part is very important. This can be found in Browse Category -> Mounts -> SVD, Tigr, Romak-3 (http://www.kalinkaoptics.com/mounts/svd-psl-tigr-romak-3.html).
(3) Stock that you will feel OK modifying (see "Preserving the original rifle" above).
(4) Bolt body that you will feel OK modifying (see "Preserving the original rifle" above).
(5) Drill bit #11, drill bit #21, 10-32 tap, T-wrench to hold the tap, and 2 10-32 x 1/2" screws. This is available in the local hardware store (for example, ACE). Get the ones that are the best quality, designed for hardened steel.
(6) Cutting oil. This is a bit hard to find, but I tracked it down in Lowe's and in ACE. Home Depot does not have it.
(7) Drill press. Local hardware store, $120-$180.
(8) Drill press vise. Home Depot, $16. A few large matching bolts, nuts, and washers to fix it to the drill press table, same source.
(9) Small bulls eye level. Home Depot.
(10) Paint stripper, for example, Citristrip (http://citristrip.com/). Sand paper (coarse and fine), steel wool (fine). Two brushes. Gloves, paper towels, 2 wood blocks, old newspapers. Local hardware store.
(11) Wood stain of your choice. You should defer picking the color until you have stripped the stock of its current paint.
(12) A rotary tool like Dremel.
(13) A gun vise or an inexpensive shooting rest. http://www.midwayusa.com/, $20-$60, depending on whether you want to have something you can use for shooting, or just mounting the gun for cleaning and scope alignment.
(14) A laser boresighter. http://www.midwayusa.com/. There is no picture here because I really cannot recommend any particular model - the choice is between an expensive and crappy one ($150 LaserLyte Kryptonyte Green Laser Boresighter 22 to 75 Caliber), and a less expensive but equally crappy one ($30 Sightmark Laser Bore Sight 243, 308 Winchester, 260, 7mm-08 Remington). Price/performance of the Sightmark is better. The above-referenced caliber (243) works for 7.62x54r, although the bolt does not close. This is OK, the bolt does not close in 308 rifles either.
Bolt body
To work with any scope mount other than the scout mount, the bolt handle needs to be turned down. This is because when the bolt is open, it's handle sticks upwards and interferes with the scope. There are several ways this can be accomplished. First, there is an ATI bolt handle kit that costs around $20 on eBay and contains the replacement handle, the drill bit, the tap, and the screw. The result does not look amazing, and requires notching the stock because the handle extends directly down when the bolt is closed.
The picture below looks nicer than the reality.
As of this writing, a bolt body with the handle turned down can be bought from here: http://www.tngunparts.com/m9130.htm for $54. I have not used them, so I do not know how exactly is the bent handle manufactured,. Sometimes they simply bend the handle down without adding to the length of it. The result is not that good, there simply is not enough handle to grab it when opening and closing the action:
(the part above is available here, http://www.gunpartscorp.com/catalog/Detail.aspx?pid=291700&catid=3258 for $34)
eBay has a number of people sell bolt bending as a service: you mail them your body, they modify the handle for you, and mail it back. I used Marvin Burrows (eBay: mellbee) several times, and he does excellent job for around $46, including shipping. This is his eBay ad:
And this is the result:
The turnaround time is about 2 weeks including the mailing time.
If you are really adventurous, you can try doing it yourself using the instructions here: http://www.gswagner.com/mosin-nagant/bolt/mnbolt.html
...or here:
http://www.opticstalk.com/topic12364.html.
Side Rail
This is the "mechanical" part of the project. You will need to drill and tap 2 holes in the receiver to attach the side rail.
To do this, you need to attach the side rail to the receiver temporarily to drill the very first hole. It goes on the left part of the receiver so that its top is close to flush with the opening in the action.
This time I suggest you remove the trigger group by unscrewing the single screw that holds it on the receiver. Mounting the receiver in the vise is hard as it is, without extra parts sticking out.
Before you mount the receiver, ensure that the drill table is horizontal by using a level. You will need this to align the receiver surface to be perfectly horizontal afterwards.
Place the rail in the side of the receiver. I do not know if there is "the" right spot. The receiver is curved, and on all 3 rifles on which I put the side rail the scope ended up pointing up and to the left relative to the barrel axis. This is OK: the problem will be corrected by shimming the mounting bracket. See the couple of pictures above for approximately right location.
The legs on the rail should obviously hug the receiver and not hang out through the action's opening.
Fix the side rail in place. You can use either a very small clamp, or wrap it tightly using electrical or duct tape. Make sure that neither cover the opening which you will drill.
Plug the chamber with a tight wad of paper towel to ensure that the metallic debris from drilling does not end up in the chamber or the barrel.
Place the drill table vise on the drill table. Do not yet attach it with the bolts. Place the receiver on the vise, tighten the vise as little as necessary so that the receiver does not slide. Guide the system so that the hole in the side rail is approximately below the drill's chuck, and at the same time all four of the mounting openings in the vise intersect with the mounting openings on the drill table.
Adjust the drill table to a height where the drill bit can be lowered sufficiently to drill through the receiver.
Put the bolts through the mounting holes. Use the washers on both sides, and screw them down so that the whole system can move about with some friction. Now place the bulls eye level on the side rail, reopen the vise jaws just a little bit so that receiver can be reoriented, and move it slightly so that the bubble of air in the level is right in the center. Reclose the vise jaws and tighten them, while monitoring the bubble - when jaws are closed the receiver might shift and the leveling action will have to be repeated.
Now that the system is aligned horizontally, put the larger drill bit in the chuck. Tighten. Do not turn the drill on yet, but lower the chuck to see where it would touch the metal. By moving the vise slightly ensure that the drill bit goes exactly through the hole in the side rail. The larger drill bit should fit tightly through that hole. When it's in, rotate it around to make sure that the system is perfectly aligned and the drill bit does not scrape the metal of the side rail.
Tighten the bolts that fix the vise on the drill table. Lower the chuck again to make sure the position did not shift. Rotate it around again.
Put the eye protection on, turn on the drill and lower the larger bit just enough to make a small crater, just the diameter of the drill but not deeper than necessary, on the steel of the receiver. Raise the chuck and replace the drill bit with the smaller one. Lower the chuck to ensure that the system is still aligned. The drill bit should touch the metal right in the middle of the crater left by the bigger drill.
If the drill has an adjustable RPM, set it to medium low (800-1200). Place a drop of the cutting oil on the receiver where it will be drilled. Note that cutting oils are toxic, do not let it anywhere near your exposed skin. Use gloves!
Drill slowly, raising the chuck to clear the metal debris out of the hole often. Do not apply a force that is more than 20lb (100N). This is very important, or the drill bit can break and stick in the hole, and it might be impossible to remove it! When the hole is drilled though, remove the receiver from the vise, and remove the side rail from the receiver. Using paper towel (and gloves!) clean all metal debris from the receiver.
Put another drop of cutting oil (gloves!) on the tap. Rotate it and guide it in the hole, maintaining perpendicular angle to the receiver. Go lightly, reversing the direction, cleaning the debris and reoiling frequently. A broken tap is a disaster - it is made of a hard alloy and if broken is next to impossible to remove.
When the thread is cut (the widest part of the tap is through the hole), remove the tap, clean the receiver and the new thread using paper towels. You can now screw the side rail to the receiver using the newly made hole and one of the screws, and repeat the process for the next hope.
Useful hint: when tapping the second hole, keep the side rail in place (but clean the drilling debris out!), it will help guide the tap.
Stock
This is the last part of the project. Now that we have a rail on the side of the receiver, the stock will not fit and a cut out needs to be made to accommodate the part that is sticking out. Also, the height of the side rail is somewhat smaller than the thickness of the stock, so a small layer of wood needs to be removed from the left side of the stock so that the rail is exposed enough.
Because quite a bit of finish will be removed to accommodate the rail, we will need to refinish the stock. If you have done this before, just go with what you know, not what I write here. I am a complete novice to wood finishing, and the results I personally achieved are functional, but not beautiful.
First, use the paint remover to get the current finish off. You will need a brush, a paint stripper, steel wool and sand paper for this.
Citristrip is a paint stripper that can be used indoors, other must be used outside. Make sure that the weather is right! Vast majority of them are health hazard so be cautious and read the instructions before starting. I found that a combination of Citristrip followed by the classic stain remover works well.
Although most of the paint/wax/whatever it is will come off, some coloring will still remain.
You can probably get closer to clean wood by sanding it off with sandpaper.
After you got as much previous stain off as you think is practical, pick the stain that will (1) survive outdoors, and (2) will either match the previous stain closely or be dark enough to cover the remaining traces of the older stain. I chose the later route, so that's what you see in the pictures.
Place the barrel in the receiver and mark the places where the stock interferes with the side rail. Using the rotary tool and the sanding band...
...remove the side of the stock about 1/2 of the width of the rail. Use the cutting attachment...
...to take care of the corners. Replace the receiver to see how much the opening needs to be deepened. Keep doing this until the screwed down receiver can go into the stock all the way and the side rail still does not touch the stock.
Now take the scope or the mounting bracket and try to slide it onto the rail. You will see that the side of the stock prevents it from engaging. Again, using the rotary tool keep removing thin layers of the side until the scope mount can slide onto the rail.
Take a look at the picture below and note the depression cut out on the stock to accommodate the externalities of the scope mount.
After the barreled receiver fits (do not forget to screw it in and tighten the screws before ensuring that the rail does not touch the stock), and the scope mounting bracket fits on the rail, you are ready to apply the stain to the stock.
Disassemble the rifle back. Using the instructions for your stain and working in an open space (the fumes are toxic!), apply a coat of stain, let it dry, then repeat twice, applying the total of 3 layers.
After the stain dries completely (this will take a day), reassemble the rifle fully.
Adjusting the scope mount
As I said above, the side rail will not be precisely aligned with the barrel axis. In all my mounts "out of the box" the scope will point high and to the left. This misalignment may or may not be correctable by the scope's internal adjustment mechanism, but it is much better to instead adjust the scope mount so that the scope's natural axis is in alignment with the barrel.
There are a few reasons for aligning the mount instead of adjusting the scope.
First, the mount is probably pointing high. Even if you can adjust the elevation on the scope, your scope will be close to out of the adjustment range pointing down. So when you would want to move it down for shooting at 200/300 meters, it is very likely that you will not be able to do it because scope's adjustment range will already have been used to compensate for the rail.
Second, scopes near the edge of their adjustment ranges tend to not keep zero as well as they do when they are centered.
Adjusting the Dragunov-type mount is actually very easy. The bracket's top rail is attached to the middle part by two screws, and the middle part attaches to the part that goes on the side rail with 4 screws. The windage (horizontal) adjustment is achieved by putting shims between the middle and the bottom part, and the vertical adjustment is achieved by shimming the rail.
I use aluminum strips from soda cans for shims - they can be stacked to achieve exactly the necessary thickness.
Attach the scope to the mount. Ensure that the scope's optical axis is centered. To do this, loosen the scope in the rings and rotate it while observing the cross hairs through the eyepiece. If the scope axis is centered, the impact point will be the same while the scope rotates. Use windage and elevation adjustments to center the scope. When the scope is centered, tighten the rings.
Turn the laser boresighter on and put it into the chamber. Put the gun in a vise and point it to the wall some distance away (10 meters or more, depending on the minimum distance at which your scope still focuses). Note where the scope's cross hairs are, relative to the laser beam.
Turn the boresighter off. You will need to make several measurements, and the batteries are only good for minutes (despite what the instructions claim).
Disassemble the scope mount, and measure the sizes of the holes and distances between them.
Cut off several rectangular pieces of aluminum foil from the side of a soda can. Initially make them much larger than is really needed. For the top shims you will need to drill one big and one very small hole next to each other. For the bottom shim, you will need two holes of the same size. The drill press will help here.
It is easier to drill the holes when multiple layers of the aluminum are bunched together. After the holes are done (plan to waste a few pieces to practice) you can cut around them to size.
Add a few shim pieces, reassemble the mount and replace the scope. Turn the laser boresighter on and observe the new impact point.
The goal is to have the cross hairs about 1"-1.5" ABOVE the laser mark at 10 meters. The actual scope axis is about 2" above the barrel axis, but you want to make the centered scope point a little bit DOWN so that it does not run out of DOWNWARD alignment when shooting at distances beyond 100 meters (to track the bullet trajectory the scope gets turned down as the target is farther away).
You will have to do a few passes to get the scope almost right. It does not have to be completely on target - the last final touches are worked out using the scope's internal adjustment mechanisms. Do not spend too much time on it until you get to the range though - the accuracy of the laser boresighter is only within 10" at a 100 meters, if even that. It will get you on paper and you will use the scope's controls to get on target from there.
Saturday, August 21, 2010
How to make a sniper rifle. Part 6: Selecting a scope mount.
[This is the part 6 of the series. Table of contents: http://1-800-magic.blogspot.com/2010/08/how-to-make-sniper-rifle-table-of.html]
Mounting a scope is by far the most challenging issue when dealing with Mosin Nagants. The rifle was designed before scopes were used in combat, and made before they became accessible to an average soldier. In WWII rifle scopes were present on only a tiny percentage of weapons specifically designated as sniper rifles.
This is why, unlike a typical modern military or hunting rifle, a Mosin you can buy today has no way of mounting a scope - the exception being "sniper" variants which I will discuss below. To mount a scope the rifle will need to be modified to various degrees, some scope mounts requiring more, and some less.
In this post I discuss various mounting options in detail.
"Authentic" military mounts
I have already pointed out, in the buying section that you can get a "sniper" version of Mosin Nagant with the scope pre-installed for $400-$500. These are not actually true sniper rifles from WWII, but rather standard issue Mosin Nagants with a reproduction scope added recently. Judging from what I have seen at the range, these rifles can be spectacularly inaccurate (the dispersions I've seen with people shooting them were as bad as 10 inches at a 100 yards).
There is a small number of authentic sniper rifles on the market with real WWII scopes. You should expect to pay around $800-$1200 for them.
There are two types of military scopes for Mosin Nagant. The first one, used mostly in the late 1930s, was called PE. It has a 4x magnification, a German post reticle, a design that is similar to a modern rifle scope, and mounted directly on top of the receiver.
The mount itself was attached to the receiver with 6 screws. After the mount was attached, the iron sights could no longer be used.
During the WWII this scope was replaced by a side-mounted PU scope. It has a slightly lower magnification of 3.5, and a "flat" design where the diameter of the scope tube is the same as the diameter of the objective.
While PE mount can be used with more modern scopes (with 30 mm tube diameter) - provided that the bell fits, since the mount is low, - the PU scope design depends on the scope's objective being the same diameter as the tube, since the scope band is one piece and only has tightening screws on one side:
So it really only works with the original scope. The advantage of PU mount is the side rail which allows quick removal of the scope. Also, the mount allows the use of iron sights even when the scope is attached. However, installing the side rail requires modifying the stock.
Both mount types require the use of a special "turned down" bolt, since when opened, the bolt handle sticks upwards and would interfere with the scope. This is true for any scope mount, except the scout mount discussed below.
Full overview of Soviet military scopes can be found here: http://www.mosinnagant.net/sniper%20section/snipertext1.asp
While "authentic" scopes can be interesting as historical pieces of militaria (unless, of course, you install them yourself using reproduction parts), they have many disadvantages when it comes to actual shooting.
First, they have very low magnifications (3.5 for PU and 4 for PE). While it might be sufficient for human targets in the war, I hope that most people today would be shooting at paper, and you won't be able to even see a 1 inch target dot at a 100 meters with only 4x magnification.
Second, when the scope is sighted to adjust for the difference in the direction of the scope mount and the barrel, since even a tiny level of non-collinearity will lead to large difference in point of impact, in a modern scope the field moves and the cross-hair stays centered. In these older designs the cross-hair moves, so you end up with it off-center, sometimes significantly off-center.
And even if by magic your horizontal axis is the same, when you are shooting long distance you have to compensate for the bullet drop, so you will end up with this:
For these reasons I do not recommend using PU/PE scopes and instead go with more modern alternatives.
NOTE: There are after-market brackets that replace the very top of the PU mount with rings that can hold the standard 1" tube available on eBay. This allows using a modern scope with the PU scope mount.
HOWEVER, the mount was designed for a small, light scope, and so the base of the scope (the distance between the rings) is rather small. Mounting a large, heavy modern scope on these rings, coupled with a very heavy recoil of Mosin's 7.62x54r cartridge would almost certainly exert a very high stress on the scope tube, the scope will shake excessively, and will be more likely to fail.
Scout mount
Scout scopes have a very long eye relief - the distance between the eyepiece and the eye - so the scope can be mounted forward of the receiver.
For Mosin Nagant this setup is extremely convenient. The scout scope does not interfere with the bolt handle, so it does not need to be modified. It replaces the iron sights and is mounted using the hardware that goes into the iron sight mount - so there is no need to drill anything or cut the stock. The mount itself is just a cheap piece of metal and can be had for $12-$14 on ebay.
Despite the ease of installation, I do not recommend it for the following reasons.
First, the maximum magnification that is available in scout scopes is 7x. At this magnification most of 1" dot is covered by the cross-hairs at 100 yards, so getting to below 1 MOA is very challenging.
Second, only very few scout scopes are available, mostly the cheaper ones, and the cheap scopes are known to not hold the impact point very well.
Third, the mount itself holds on friction from several adjusting screws, and tends to come loose. It will certainly come loose after the first couple of shots, and you will have to remove the scope (because the adjusting screws on the mount are directly below it), retighten the screws, and remount the scope. This has to be done several times, and even after that I have doubts about how good the mount is capable of holding zero.
Finally, the iron sights are removed with this mount and are not usable.
Metal band retainer
This type of the scope is produced by an individual, not a company, and occasionally pops up on eBay for $80-$90. It consists of a base that is held on top of the receiver by a metal band wrapping around the receiver. This is another example of so called "no gunsmithing required" scope mount kits, the first being the scout mount.
This is what it looks:
...and...
Here is how it gets installed:
The only modification necessary for this mount is dremmeling out a tiny amount of wood from inside the stock to make space for the band.
You still do need to modify the bolt handle because the scope mount hangs directly over the bolt, and interferes with it when the bolt handle is raised. I will write more about turning the bolt handle in the following article.
This mount is easy to install and allows using any modern scope. However, it does not work.
When the receiver heats up when the rifle is fired, the expansion coefficient of the receiver metal is different from that of the retaining band. So the band gets stretched a little bit, and when the rifle cools back, it comes loose, so the screws that hold the band need to be retightened constantly. With every tightening the base slides alongside the receiver a little bit, and the impact point moves.
I do not recommend using this scope mount at all.
ATI scope mount
ATI kit requires drilling the receiver and replacing the bolt handle to install the scope. This is relatively demanding project, but it results in a mount that is better than any discussed previously. With this mount I have gotten pretty close to my 1 MOA goal.
The kit consists of a bracket that gets screwed on top of the receiver, the bolt handle, and the hardware (drill bits, a tap, and screws) to get everything installed. It costs in the vicinity of $40.
This is the bracket piece from the side...
...the top...
...and installed.
The receiver is drilled on top to screw the base in as follows:
The bracket hangs very low over the receiver (which is a good thing, because the distance between the optical axis of the scope and the axis of the barrel is best minimized) so the standard turned down bolts do not work, and you need to use ATI bolt handle.
The result does not look amazingly beautiful, but it does work. Because the bolt handle is turned down almost at the right angle and almost at the base of the bolt, the stock needs to be notched a bit to let the bolt close.
The drill press is absolutely required to drill both the handle and the receiver - do not even think about doing this with a hand drill!
Advantages of this kit:
(1) It is relatively cheap.
(2) It provides reasonable base that minimizes the momentum exerted on the scope during the recoil.
(3) It requires minimum modification of the stock.
(4) The result is reasonable stable and holds zero well.
Disadvantages:
(1) Aligning the bracket to the top of the receiver is very, very hard. Ideally, the bracket should be collinear to the barrel, but there is no way to actually measure this. Also, the top of the receiver is not necessarily symmetric, or aligned with the barrel, so the contact between the bottom of the bracket and the receiver will orient it in a direction you might not be able to control.
When I installed mine, it was misaligned so much that I had to use adjustable rings to compensate (Millet, $30). The problem with these rings is that because of the ring design one cannot remove and reinstall them without losing zero, so the scope has to be permanently affixed to the rifle.
This is the reason why I eventually gave up on this way of mounting the scope.
(2) You have to have a drill press. A cheap one (~$120) will do, but it is absolutely required.
(3) Aligning receiver in the vise on the drill press is hard. It has to be exactly perpendicular to the drill bit, and because it is curved, it is a non-trivial exercise. Drilling requires cutting oil which is not widely available (I was finally able to find it in Lowe's).
(4) Take extra care when tapping the receiver. If you turn too hard, or don't use cutting oil, the tap bit will break and you will end up with the hole that is plugged by a bit of hardened instrumental steel which is impossible to extricate.
Overall, the ATI kit is an acceptable way to mount the scope IF you do not require removing and reinstalling the scope frequently (or you are extremely lucky and the shape of your receiver aligns with the barrel perfectly).
Dragunov side rail
This is by far the most expensive and the hardest to install scope mount, but it gives the best overall results.
Side rail installs on the side of the receiver as follows:
It does require not only drilling and tapping the receiver, but extensive modification of the stock, including refinishing.
Once installed, however, a wide variety of scopes and scope mounts designed for Dragunov (and its AK clones such as PSL54c and Zastava M76) will work for your rifle.
For example, this is a bracket that allows installation of any scope with Weaver rings:
...or a Romanian LPS scope (4x, ~$100 currently at http://www.jgsales.com/)...
...and finally Russian POSP scope from http://www.kalinkaoptics.com/...
As I pointed out above, this is the hardest to install mount, but is preferred as far as quality and versatility of the outcome goes. I will cover the installation, including procuring all the parts, in the next post.
Mounting a scope is by far the most challenging issue when dealing with Mosin Nagants. The rifle was designed before scopes were used in combat, and made before they became accessible to an average soldier. In WWII rifle scopes were present on only a tiny percentage of weapons specifically designated as sniper rifles.
This is why, unlike a typical modern military or hunting rifle, a Mosin you can buy today has no way of mounting a scope - the exception being "sniper" variants which I will discuss below. To mount a scope the rifle will need to be modified to various degrees, some scope mounts requiring more, and some less.
In this post I discuss various mounting options in detail.
"Authentic" military mounts
I have already pointed out, in the buying section that you can get a "sniper" version of Mosin Nagant with the scope pre-installed for $400-$500. These are not actually true sniper rifles from WWII, but rather standard issue Mosin Nagants with a reproduction scope added recently. Judging from what I have seen at the range, these rifles can be spectacularly inaccurate (the dispersions I've seen with people shooting them were as bad as 10 inches at a 100 yards).
There is a small number of authentic sniper rifles on the market with real WWII scopes. You should expect to pay around $800-$1200 for them.
There are two types of military scopes for Mosin Nagant. The first one, used mostly in the late 1930s, was called PE. It has a 4x magnification, a German post reticle, a design that is similar to a modern rifle scope, and mounted directly on top of the receiver.
The mount itself was attached to the receiver with 6 screws. After the mount was attached, the iron sights could no longer be used.
During the WWII this scope was replaced by a side-mounted PU scope. It has a slightly lower magnification of 3.5, and a "flat" design where the diameter of the scope tube is the same as the diameter of the objective.
While PE mount can be used with more modern scopes (with 30 mm tube diameter) - provided that the bell fits, since the mount is low, - the PU scope design depends on the scope's objective being the same diameter as the tube, since the scope band is one piece and only has tightening screws on one side:
So it really only works with the original scope. The advantage of PU mount is the side rail which allows quick removal of the scope. Also, the mount allows the use of iron sights even when the scope is attached. However, installing the side rail requires modifying the stock.
Both mount types require the use of a special "turned down" bolt, since when opened, the bolt handle sticks upwards and would interfere with the scope. This is true for any scope mount, except the scout mount discussed below.
Full overview of Soviet military scopes can be found here: http://www.mosinnagant.net/sniper%20section/snipertext1.asp
While "authentic" scopes can be interesting as historical pieces of militaria (unless, of course, you install them yourself using reproduction parts), they have many disadvantages when it comes to actual shooting.
First, they have very low magnifications (3.5 for PU and 4 for PE). While it might be sufficient for human targets in the war, I hope that most people today would be shooting at paper, and you won't be able to even see a 1 inch target dot at a 100 meters with only 4x magnification.
Second, when the scope is sighted to adjust for the difference in the direction of the scope mount and the barrel, since even a tiny level of non-collinearity will lead to large difference in point of impact, in a modern scope the field moves and the cross-hair stays centered. In these older designs the cross-hair moves, so you end up with it off-center, sometimes significantly off-center.
And even if by magic your horizontal axis is the same, when you are shooting long distance you have to compensate for the bullet drop, so you will end up with this:
For these reasons I do not recommend using PU/PE scopes and instead go with more modern alternatives.
NOTE: There are after-market brackets that replace the very top of the PU mount with rings that can hold the standard 1" tube available on eBay. This allows using a modern scope with the PU scope mount.
HOWEVER, the mount was designed for a small, light scope, and so the base of the scope (the distance between the rings) is rather small. Mounting a large, heavy modern scope on these rings, coupled with a very heavy recoil of Mosin's 7.62x54r cartridge would almost certainly exert a very high stress on the scope tube, the scope will shake excessively, and will be more likely to fail.
Scout mount
Scout scopes have a very long eye relief - the distance between the eyepiece and the eye - so the scope can be mounted forward of the receiver.
For Mosin Nagant this setup is extremely convenient. The scout scope does not interfere with the bolt handle, so it does not need to be modified. It replaces the iron sights and is mounted using the hardware that goes into the iron sight mount - so there is no need to drill anything or cut the stock. The mount itself is just a cheap piece of metal and can be had for $12-$14 on ebay.
Despite the ease of installation, I do not recommend it for the following reasons.
First, the maximum magnification that is available in scout scopes is 7x. At this magnification most of 1" dot is covered by the cross-hairs at 100 yards, so getting to below 1 MOA is very challenging.
Second, only very few scout scopes are available, mostly the cheaper ones, and the cheap scopes are known to not hold the impact point very well.
Third, the mount itself holds on friction from several adjusting screws, and tends to come loose. It will certainly come loose after the first couple of shots, and you will have to remove the scope (because the adjusting screws on the mount are directly below it), retighten the screws, and remount the scope. This has to be done several times, and even after that I have doubts about how good the mount is capable of holding zero.
Finally, the iron sights are removed with this mount and are not usable.
Metal band retainer
This type of the scope is produced by an individual, not a company, and occasionally pops up on eBay for $80-$90. It consists of a base that is held on top of the receiver by a metal band wrapping around the receiver. This is another example of so called "no gunsmithing required" scope mount kits, the first being the scout mount.
This is what it looks:
Here is how it gets installed:
The only modification necessary for this mount is dremmeling out a tiny amount of wood from inside the stock to make space for the band.
You still do need to modify the bolt handle because the scope mount hangs directly over the bolt, and interferes with it when the bolt handle is raised. I will write more about turning the bolt handle in the following article.
This mount is easy to install and allows using any modern scope. However, it does not work.
When the receiver heats up when the rifle is fired, the expansion coefficient of the receiver metal is different from that of the retaining band. So the band gets stretched a little bit, and when the rifle cools back, it comes loose, so the screws that hold the band need to be retightened constantly. With every tightening the base slides alongside the receiver a little bit, and the impact point moves.
I do not recommend using this scope mount at all.
ATI scope mount
ATI kit requires drilling the receiver and replacing the bolt handle to install the scope. This is relatively demanding project, but it results in a mount that is better than any discussed previously. With this mount I have gotten pretty close to my 1 MOA goal.
The kit consists of a bracket that gets screwed on top of the receiver, the bolt handle, and the hardware (drill bits, a tap, and screws) to get everything installed. It costs in the vicinity of $40.
This is the bracket piece from the side...
...the top...
...and installed.
The receiver is drilled on top to screw the base in as follows:
The bracket hangs very low over the receiver (which is a good thing, because the distance between the optical axis of the scope and the axis of the barrel is best minimized) so the standard turned down bolts do not work, and you need to use ATI bolt handle.
The result does not look amazingly beautiful, but it does work. Because the bolt handle is turned down almost at the right angle and almost at the base of the bolt, the stock needs to be notched a bit to let the bolt close.
The drill press is absolutely required to drill both the handle and the receiver - do not even think about doing this with a hand drill!
Advantages of this kit:
(1) It is relatively cheap.
(2) It provides reasonable base that minimizes the momentum exerted on the scope during the recoil.
(3) It requires minimum modification of the stock.
(4) The result is reasonable stable and holds zero well.
Disadvantages:
(1) Aligning the bracket to the top of the receiver is very, very hard. Ideally, the bracket should be collinear to the barrel, but there is no way to actually measure this. Also, the top of the receiver is not necessarily symmetric, or aligned with the barrel, so the contact between the bottom of the bracket and the receiver will orient it in a direction you might not be able to control.
When I installed mine, it was misaligned so much that I had to use adjustable rings to compensate (Millet, $30). The problem with these rings is that because of the ring design one cannot remove and reinstall them without losing zero, so the scope has to be permanently affixed to the rifle.
This is the reason why I eventually gave up on this way of mounting the scope.
(2) You have to have a drill press. A cheap one (~$120) will do, but it is absolutely required.
(3) Aligning receiver in the vise on the drill press is hard. It has to be exactly perpendicular to the drill bit, and because it is curved, it is a non-trivial exercise. Drilling requires cutting oil which is not widely available (I was finally able to find it in Lowe's).
(4) Take extra care when tapping the receiver. If you turn too hard, or don't use cutting oil, the tap bit will break and you will end up with the hole that is plugged by a bit of hardened instrumental steel which is impossible to extricate.
Overall, the ATI kit is an acceptable way to mount the scope IF you do not require removing and reinstalling the scope frequently (or you are extremely lucky and the shape of your receiver aligns with the barrel perfectly).
Dragunov side rail
This is by far the most expensive and the hardest to install scope mount, but it gives the best overall results.
Side rail installs on the side of the receiver as follows:
It does require not only drilling and tapping the receiver, but extensive modification of the stock, including refinishing.
Once installed, however, a wide variety of scopes and scope mounts designed for Dragunov (and its AK clones such as PSL54c and Zastava M76) will work for your rifle.
For example, this is a bracket that allows installation of any scope with Weaver rings:
...or a Romanian LPS scope (4x, ~$100 currently at http://www.jgsales.com/)...
...and finally Russian POSP scope from http://www.kalinkaoptics.com/...
As I pointed out above, this is the hardest to install mount, but is preferred as far as quality and versatility of the outcome goes. I will cover the installation, including procuring all the parts, in the next post.
Tuesday, August 10, 2010
How to make a sniper rifle. Part 5: Accurizing a Mosin Nagant
[This is the part 5 of the series. Table of contents: http://1-800-magic.blogspot.com/2010/08/how-to-make-sniper-rifle-table-of.html]
When it comes to any rifle's accuracy, excluding the optics and the ammunition, there are 5 attributes of the rifle itself:
1) Rigidity of the barrel
2) Quality of the bore
3) Weight of the trigger
4) Contact between the receiver and the stock
5) Contact between the barrel and the stock
We don't have any control over #1, the rigidity of the barrel was fixed when the gun was designed.
We can only control #2 when we buy the rifle. Make sure you inspect the bore carefully when you buy in at the retail store, or pay extra $30 to J&G Sales so they do it for you when you buy it on the internet.
#3, the weight of the trigger is the force with which the trigger needs to be pulled for the rifle to go off. A typical military rifle has a 8lb trigger weight. a typical benchrest rifle's trigger pull is measured in ounces. The heavier the trigger, the more the rifle is deflected by the finger pulling the trigger, the more variance on the impact point and the wider is the group.
A Mosin trigger is an extremely simple system, it is typically very heavy, and has no support for adjustment. You can lighten it somewhat by shimming it with thin pieces of aluminum (e.g. cutouts from the soda cans) by putting them between the receiver and the base of the trigger spring, but unless you are ABSOLUTELY SURE that the rifle will only be loaded at the range and only when pointing towards the target, I STRONGLY recommend against doing it. A trigger modified in this way can go off on its own - or if the rifle is struck - at any point, which makes the rifle extremely dangerous.
So it is #4 and #5 that an amateur (and not so amateur) gunsmith can control to improve the accuracy of his or her rifle. This is what I am going to describe here.
The rules around the stock are extremely easy: you should avoid having barrel touch the stock at all costs; conversely, the receiver should contact the stock as tightly as possible. The techniques that ensure that are called "free floating the barrel" and "glass bedding the receiver".
Free floating the barrel
Given a very long stock that goes almost all the way to the muzzle this is hard to do without cutting off much of the forward section of the stock. Instead of doing this, you can sand a thin layer from the internal channel of the bottom part, remove the hand guard, and put a piece of cork board between the barrel and the tip of the stock:
To test that there is no contact between the stock and the barrel, put a dollar bill between the stock and the barrel forward of the corkboard shim and slide it towards the receiver. The paper should slide freely.
Glass bedding the receiver
If the shot group has a wide (2"-3") dispersion in the vertical axis the culprit is almost always the bad contact between the stock and the receiver. To fix this, the receiver is "bedded" into the stock with a layer of epoxy. Alongside free floating the barrel, this is the best way to improve the accuracy of an existing gun.
To do this, the bottom layer of the receiver is covered with a release agent to make sure that epoxy does not glue it to the stock, the layer of epoxy is then placed on the stock near the recoil lug (the front part of the receiver), and the rear screw.
The receiver is screwed in lightly, the layer of the epoxy that squeezes out from the sides is removed, and it is left to sit for a period of time.
When the epoxy hardens, the receiver is lifted out of the stock, the release agent is cleaned off. Then the gun is put back together using normal (high) tension on the screws, and left alone for another 4-5 days until the epoxy cures completely.
The results should look something like the following.
1) Recoil lug
2) Rear screw
A few tips...
1) I have used both the Acraglas Gel (you can find it at http://www.brownells.com/) and JB Weld (the technique is described here: http://www.theboxotruth.com/docs/edu75.htm) and the results seem to be the same with JB Weld being much cheaper ($6 vs. $25).
2) If you do use Acraglas, be sure to use the car wax as a release agent (again, see here: http://www.theboxotruth.com/docs/edu75.htm for the pictures), the release agent that ships with the kit does not work very well.
3) Less is more in this case. You can always repeat the process if you put too little, but if you put too much, you will have sticky goo all over your stock, the barrel, and the receiver that will be hard to get off.
4) Remove a 2-3 mm layer of wood saturated with oil and lacquer from the bedding area using a Dremmel tool. If you don't, the epoxy mold may not stick, or you will have contact problems between the bedding and the wood.
5) If you use Acraglas, be sure to read the manual completely before starting.
When it comes to any rifle's accuracy, excluding the optics and the ammunition, there are 5 attributes of the rifle itself:
1) Rigidity of the barrel
2) Quality of the bore
3) Weight of the trigger
4) Contact between the receiver and the stock
5) Contact between the barrel and the stock
We don't have any control over #1, the rigidity of the barrel was fixed when the gun was designed.
We can only control #2 when we buy the rifle. Make sure you inspect the bore carefully when you buy in at the retail store, or pay extra $30 to J&G Sales so they do it for you when you buy it on the internet.
#3, the weight of the trigger is the force with which the trigger needs to be pulled for the rifle to go off. A typical military rifle has a 8lb trigger weight. a typical benchrest rifle's trigger pull is measured in ounces. The heavier the trigger, the more the rifle is deflected by the finger pulling the trigger, the more variance on the impact point and the wider is the group.
A Mosin trigger is an extremely simple system, it is typically very heavy, and has no support for adjustment. You can lighten it somewhat by shimming it with thin pieces of aluminum (e.g. cutouts from the soda cans) by putting them between the receiver and the base of the trigger spring, but unless you are ABSOLUTELY SURE that the rifle will only be loaded at the range and only when pointing towards the target, I STRONGLY recommend against doing it. A trigger modified in this way can go off on its own - or if the rifle is struck - at any point, which makes the rifle extremely dangerous.
So it is #4 and #5 that an amateur (and not so amateur) gunsmith can control to improve the accuracy of his or her rifle. This is what I am going to describe here.
The rules around the stock are extremely easy: you should avoid having barrel touch the stock at all costs; conversely, the receiver should contact the stock as tightly as possible. The techniques that ensure that are called "free floating the barrel" and "glass bedding the receiver".
Free floating the barrel
Given a very long stock that goes almost all the way to the muzzle this is hard to do without cutting off much of the forward section of the stock. Instead of doing this, you can sand a thin layer from the internal channel of the bottom part, remove the hand guard, and put a piece of cork board between the barrel and the tip of the stock:
To test that there is no contact between the stock and the barrel, put a dollar bill between the stock and the barrel forward of the corkboard shim and slide it towards the receiver. The paper should slide freely.
Glass bedding the receiver
If the shot group has a wide (2"-3") dispersion in the vertical axis the culprit is almost always the bad contact between the stock and the receiver. To fix this, the receiver is "bedded" into the stock with a layer of epoxy. Alongside free floating the barrel, this is the best way to improve the accuracy of an existing gun.
To do this, the bottom layer of the receiver is covered with a release agent to make sure that epoxy does not glue it to the stock, the layer of epoxy is then placed on the stock near the recoil lug (the front part of the receiver), and the rear screw.
The receiver is screwed in lightly, the layer of the epoxy that squeezes out from the sides is removed, and it is left to sit for a period of time.
When the epoxy hardens, the receiver is lifted out of the stock, the release agent is cleaned off. Then the gun is put back together using normal (high) tension on the screws, and left alone for another 4-5 days until the epoxy cures completely.
The results should look something like the following.
1) Recoil lug
2) Rear screw
A few tips...
1) I have used both the Acraglas Gel (you can find it at http://www.brownells.com/) and JB Weld (the technique is described here: http://www.theboxotruth.com/docs/edu75.htm) and the results seem to be the same with JB Weld being much cheaper ($6 vs. $25).
2) If you do use Acraglas, be sure to use the car wax as a release agent (again, see here: http://www.theboxotruth.com/docs/edu75.htm for the pictures), the release agent that ships with the kit does not work very well.
3) Less is more in this case. You can always repeat the process if you put too little, but if you put too much, you will have sticky goo all over your stock, the barrel, and the receiver that will be hard to get off.
4) Remove a 2-3 mm layer of wood saturated with oil and lacquer from the bedding area using a Dremmel tool. If you don't, the epoxy mold may not stick, or you will have contact problems between the bedding and the wood.
5) If you use Acraglas, be sure to read the manual completely before starting.
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