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7.62x54 reloads for Mosin-Nagant M-38 carbines
Toscano
Member Posts: 2 ✭✭
I'd like to work up a reload to fire in my Mosin-Nagant carbine. The original cartridge was designed for the rifle barrel (26 inches?) Has anyone worked up a load to reduce flash, unburned powder and blast from the short carbine barrels (M38 & M44)? I would like to stick to the 150 grain bullet. I would appreciate any input that would give me a starting point or someone's successful formula with this round.
Comments
When I switch to carbine length barrels, I usually have to re-formulate all of the loads that I intend to use in the shorter barreled rifles. This is almost mandatory with a barrel length change from 28-3/4" down to 20-1/4" since, as you observe, there is a substantial amount of muzzle flash and unburned powder. Unfortunately, there isn't much you can do about the noise because the shorter barrel brings the noise closer to your ears and face. But you can solve some of each of the other two problems by doing some component testing and using a chronograph to develop new loads.
The first thing I would do is slug the barrel for the groove size in order to pick the right diameter bullets.
The second thing to do is measure the chamber for Overall Length. Long chambers and standard OAL's yield lower pressure and short chambers with standard OAL's will yield higher pressure.
What you're trying to do is achieve a balance between the amount of powder and the pressure created to arrive at an efficient load that burns all the powder in the barrel, reducing muzzle flash and yet leaves the barrel fairly clean. The cooler the plasma is as it exits the barrel, the less muzzle flash. That's why carbine length barrels are notorious for muzzle flash. The loads were developed for longer barrels where the plasma can cool slightly before the bullet leaves the muzzle.
I broke down the basic metric information that the Russians used to manufacture the loads for this cartridge with a 148 gr. bullet:
Bullet = 148 gr.
Overall Length = 3.040"
Velocity = 2746 FPS.
Pressure = 41450 PSI.
The pressure ceiling is obviously set for the older original lower pressure rifles and has to carry on in order to preserve safety. If you shorten the Overall Length, you are essentially raising the pressure so if you want more of the bullet in the case be sure to watch for signs of pressure. That's why I suggest working on load development with a chronograph, you are using the velocity as an indicator which is measurable by most of us, while measuring pressure is a little more difficult. Sticking with the above parameters, it's pretty easy to work backwards using a chronograph and some starting loads. Take into consideration some of the properties of the various faster burning propellants. Most of the powder manufacturers have that information on their websites.
You need to work with some of the newer or newly re-formulated, faster powders. Some of the older style ball powders, while burning at a faster rate, actually create muzzle flash and also foul the bore more than some of the new powders. I suggest that you start with:
V V N-135
Ramshot Big Game
Re-15
AA-2520
Using any of these powders at the pressure recommended to get the velocity listed will result in all of the powder burning cleanly and completely in the barrel.
I have also used some lot #'s of IMR-3031 that worked great. Don't forget to test different primers as they can have an impact on both muzzle flash and fouling in the barrel.
As an added thought, while the 150 gr. Spitzers are nice to shoot, you can gain a ballistic advantage by using the heavier 180 gr. bullets. The loads can burn more efficiently with less of the drawbacks when using a heavier bullet. Even the 165/168 gr. can make a difference.
Here are a couple of articles that can add a little to your search:
http://7.62x54r.net/MosinID/MosinAmmo.htm (great coverage)
http://www.surplusrifle.com/shooting2006/lastbullet/6.asp
Best.