NOTE: This is an OUTDATED version. Please see http://AceMosinNagant.com/Manuals for the up-to-date instructions and products.
Mosin Nagants are excellent surplus rifles that are cheap to own and shoot, very reliable and can be accurate if you are willing to do some simple DIY shimming with aluminum alloy shims and cork rubber gaskets.
Improving the accuracy of the Mosin Nagant
When it comes to rifle accuracy, there are three fundamental factors: Consistency of the rifle, consistency of the cartridge, and consistency of the shooter. In this article, I will only talk about how to improve the consistency of the rifle using the ACE laser-cut Mosin Magant shims and cork gaskets. To evaluate the result, I recommend you use the same cartridges (can be surplus ammo) for the before/after comparison, and the same shooter of course. Also, to reduce the human error with the iron sight, I recommend you install a solid Mosin Nagant scout mount, and smooth the trigger if you can or let a gun smith do the trigger job for you.
Bolt:
An accurate rifle must have a bolt that fit properly and hold the cartridge correctly in the chamber. When you purchase a Mosin Nagant, make sure you choose one with a tight fit bolt. Google "how to choose a mosin nagant" and you can find a lot helpful suggestions online.Trigger group:
A crisp and clean trigger is another very important factor that affects the accuracy. Again, make sure you pick up a Mosin with smooth trigger pull when you buy it. You can also "polish" the trigger either by yourselves or have a gun smith to do it. There's plenty tutorials if you google it.Barrel:
Choosing a rifle with strong rifling, clean, straight barrel and smooth crown is very important to the accuracy and should be done when you purchase the firearm.Mosin Nagangs have very long barrels. When it is fired the barrel vibrates like a violin string. Pressure at the wrong points can disturb the vibrations, causing the bullet to go astray. The rubberized cork gaskets included in this accurizing kit will establish consistent and permanent pressure points between the stock and the barrel. It will also absorb and dampen most of the harmonics from the muzzle caused by the firing power.
Stock:
There are more than 17 million Mosin Nagants were made by the end of WWII. In today's North American market, the majority of them are arsenal refurbished (especially if your rifle costs only around $100). So the stocks may have seen a lot of actions already. Since wood is much softer than steel, the contact points of the stock are very likely have been"compressed" substantially after being used so many times in many years. The aluminum alloy shims in this Ace accurizing kit will help establish a stronger "skeleton" between the stock and the action, making the whole structure more consistent.Sights:
It is not in the scope of this article to discuss how to improve the iron sights.If you want to scope your Mosin, I recommend the Ace solid scout mount that replaces the whole rear iron sight base (not the ones that only replaces the leaf) because it provides a solid base, is easy to install (not drilling and tabbing, not even loctite is required) and not expensive. Best of all, you don't need to alter your bolt handle, which can be a pita and cost you $$$.How to install the ACE laser-cut Mosin Nagant shims and cork gaskets
Using shims to improve Mosin Nagant accuracy is not a new invention. It has been proven to be very effective and had been adapted by Finnish army to improve accuracy.In his book "Competitive Shooting",A.A. Yur'yev, one of the most famous and successful Soviet shooting coaches revealed the following 3 methods that can improve Mosin Nagant's accuracy:
1. Build a solid and stable platform for the action
This is the most important factor in the Mosin Nagan accurizing. After many years of use, most Mosin Nagans' wood stock has "sunk" because wood is softer than steel. When the rifle is fired, the huge recoil will cause the barrel and the receiver to vibrate. If the receiver is not securely locked to the stock , the vibration will cause a series random collision among the stock, the receiver and barrel, the trigger group and hand guard. And the collision points will be different every time when the rifle is fired. This inconsistency will affect the rifle's accuracy significantly. Even if the stock is in good condition, it is still a good practice to install the shims. Because the metal shims can spread the force evenly across the wooden stock and protect the it from being compressed by the steel rifle parts.First, add shims and gasket between the stock and receiver:
In his book, A.A. Yur'yev suggests installing three shims/gaskets in the receiver area to create a tight and even contact between the receiver and the stock:
The goal here is to free-float the barrel in the stock channel so that we have just enough space to add the cork gaskets at the front barrel band area to create a permanent pressure point that absorbs and dampens the harmonics from the muzzle:
At the chamber area (A), add the cork gasket A. Dry-fit and cut if necessary, then lightly oil the surface that contacts the chamber with your gun oil before install it.
NOTE: Always dry-fit shims and gaskets first, file or cut if needed. We've tried our best to make this kit universal-fit. However, due to the large varieties of Mosin Nagants. You may need to do some tiny adjustment yourselves.
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| Dry fit the cork gasket Mark and cut if needed |
Second, add shims between the trigger assembly and stock
Yur'yev also suggests that there should be a 1 to 3 mm gap between the receiver and the trigger group. In the ACE accurizing kit, we use T6061 aluminum shims (3 and 4) for the trigger assembly screws to create this gap. Start with 1 piece of shim each (0.8mm thick) at locations 3 and 4. This should create enough space for most Mosin Nagants unless yours has a very worn out stock. In that case add the other piece to #3 and #4.
Since there is no way to measure the gap after the rifle is assembled, the only way to know if you need another layer or not is to test and try. Together, shims 1,2,3 and 4 create a very strong and consistent platform. After the two action screws are securely tightened, the force is evenly distributed across the wooden stock.
2. Make sure the barrel channel is even and smooth
After years of heat, moisture and usage, the wooden stock and handguard may be warped, creating uneven pressure points to the barrel. First check by hand see if the stock channel and the handguard channel is smooth. If there's significantly high points, wrap the 120 grit sand paper in a 1/2 inch socket and sand the barrel channel until it's smooth.NOTE: The purpose here is only to remove the high points. Do NOT remove too much wood.
When the stock and the handguard both look and feel smooth, assemble the barrel, stock and trigger assembly (but leave the handguard along), tighten the two action screws to between 35 in/lbs and 50 in/lbs. You can start from 35 in/lbs, record your group sizes and try 40 in/lbs, 45 in/lbs until you find the best setting for your rifle. If you don't have a torque screw driver, that's OK. Just make sure you hand-tighten the two screws securely to the same level of torque.
Now perform the "dollar bill test":
With a fresh dollar bill, or a piece of print paper, run it along the entire length of the barrel channel. It should travel without hanging up.
If the barrel contacts the stock in a large section, for example, the front of the barrel, or the whole section near the chamber, it may be caused by the over compressed stock at either the tang area (1) or the recoil screw area (2). Try add/remove one piece of shim at a time at spot 1 or 2 and test again, until the barrel aligns parallel to the stock.
If the barrel is parallel to the stock but there is still some uneven contact points, mark them with a pencil, dissemble the rifle and sand the barrel channel using the earlier socket-sander method , until the paper passes the channel freely. Now you have a free-float barrel when the handguard and barrel bands are not installed.
3. Establish permanent pressure points on the barrel
In the previous step, it looks like we've got a free-float barrel. However, that is not entirely true. You will not get a true free-float barrel with the original stock of Mosin Nagant. The barrel channel is so long that it almost go all the way to the muzzle, so after the hand guard and the front barrel band are installed, the barrel is firmly "clamped" in the handguard and the lower stock. The random pressure points between the barrel and the stock will have negative impacts to the rifle accuracy. When the rifle is fired, the long, tapper barrel vibrates like a snake and "whips" the stock and handguard at random spots, especially at the front part near the muzzle where the barrel is much thinner.To mitigate this problem, Russians came up with an oiled canvas padding method. It has been proven to be effective and very practical as well because both canvas and oil are easy to find on the battle field. The canvas wrapping around the fore part of the barrel absorbs most of the harmonics from the muzzle. Also instead of having the barrel contacts the stock directly, the canvas acts as a buffer between the barrel and the stock and creates a single, permanent pressure point.
In stead of the canvas felt, this Mosin Nagant accurizing kit comes with rubberized cork gaskets. Comparing to the historical canvas felt, cork rubber gaskets are highly compressible, flexible, impact-resistant and are more shock absorbing. They are also resistant to oil, fungus and weather conditions. Hence a more permanent solution comparing to the canvas felt.
Dissemble the rifle, oil the cork gaskets lightly using gun oil to create a seamless seal between the barrel and the gasket. Do not soak the gasket in the oil like you would do to the canvas belt. The rubberized cork is already perfectly flat.
Lay the gaskets in the front barrel band section (dry fit and cut if necessary) - one in the stock channel (B) and one in the hand guard channel (C).
Reassemble the rifle. After the front barrel band is put back on, the cork rubber gaskets will create a soft "cushion" that absorbs and dampens the harmonics from the muzzle.
To verify the result, insert a paper between the two metal parts at the top of the handguard and lower stock. There should be NO contacts between them and the barrel:
Congratulations! You have successfully created a solid platform for the action and chamber, semi-free float the Mosin Nagant barrel, and create a single, permanent pressure point near the muzzle that absorbs and dampers the harmonics. It's time to take your Mosin Nagant to the range and check for the result!
