Full length stock causing accuracy problems?

[jsalcedo]

I've noticed on two of my Milsurp rifles, a M91 mosin nagant and a SMLE MKIII the accuracy starts to degrade somewhat after firing 30 rounds in quick succession.

One person told me that was a problem with guns that have stocks that run the length of the barrel. This person said the barrel heats up and does not contact the wood evenly, pushing the barrel out of alignment, causing a decrease in accuracy.


Is there any truth to this? If it is true is there any fix?

I'm under the assumption that these rifles were meant to be fired rapidly and often in combat. I usually bring a couple hundred rounds for each rifle
and spend a couple hours putting these old guns through their paces.

I have a couple of other rifles with stocks that only reach part way down the barrel and they seem to be more consistant even when hot.

Thanks in advance for any wisdom on this.

 

[Mannlicher]

That might hold water with beat up milsurp rifles. I have a gaggle of full length stocked rifles, Mannlicher-Schoenauers, Rugers, and some custom rifles. I have not experienced any accuracy problems at all.

 

[Art Eatman]

There won't be the quality of the bedding of the forearm in a milsurp that Mannlicher has in his.

If, for instance, a barrel band binds the stock rather tightly to the barrel, or the muzzle band is tight, it's possible for the difference in expansion rates of steel and wood to change the pressure of the stock on the barrel. This commonly will result in a vertical string, rising with barrel temperature.

If, with heating the group spreads out in some nonuniform manner, I would expect there are other factors than just the bedding.

Art

 

[Sir Galahad]

Never seen this before on my rifles. Of course, it depends on how one defines "degrading" accuracy. I just got a Finnish Mosin Nagant M-39 and this rifle is VERY accurate and I put 100 rounds through it one afternoon. On that note, you may wish to look into a Finnish M-39. It has a bit of a heavier barrel than a regular Mosin. I got a "excellent" condition VKT from Wholesale Guns & Ammo and the barrel is actually closer to "new, never fired" and I suspect it may be new. This M-39, as I said, is very accurate and 30 rounds is only getting it started.

 

[Keith]

Military rifles were never designed for pinpoint accuracy.

I remember reading that the K98 had a minimum accuracy standard of something like 5 MOA - actually, it was something like had to keep 40 rounds within a square measuring approximately 8x10" at 200 meters.

Of course, most of them are capable of greater accuracy than that, but designers and military boards were not concerned very much with the rifles accuracy and didn't ask for much. They envisioned thousands of men laying down volley fire at long ranges where a "hit" would be mere chance anyway. At closer ranges, even a rifle with poor accuracy will still be capable of a center-of-mass hit.

At any rate, they chose to use full length stocks so that the rifle barrel was protected when used as a club or otherwise abused in combat. And as Art points out, this will bind up the barrel in extended shooting sessions. How much this degrades accuracy will depend on the individual rifle.

Keith

 

[jsalcedo]

Thanks everyone for the great info.

I guess there is something to it afterall.

Yes, my mosin can hit an 8x10 at 200 yards when hot and so can my SMLE.

Maybe with added practice and slowing down I can trim that down a bit.

I'm wondering if loosening the barrel bands will help?

 

[benEzra]

TAPCO (www.tapco.com) also sells a synthetic Monte-Carlo-style stock for the Mosin-Nagant (all models) that leaves most of the barrel uncovered--might help accuracy if differential expansion were the problem. It requires no gunsmithing, so you can switch back and forth between stocks while leaving the rifle in its original condition.

 

[Sir Galahad]

Just got back from putting another 100 rounds through my Finn M-39. Accuracy at shot 100 was just as wonderfully precise as shot 1. You might look into a Finn. You'll be amazed.

 

[Cthulhu]

Agreed about the Finn Mosins. My M39 shoots fantasitcally. My Finn M28/30 is even better. My 91/30 Sniper is no slouch either. Nor my stocked to the muzzle Swede M94 carbine.
I've never found the handguards to affect this, but bear in mind that on the some of the Finns the handguards are shimmed by internal aluminum spacers to prevent contact between the barrel and guard. That certainly may contribute to accuracy as the barrels get warm. Also remember that a lot of military rifles have rather long skinny barrels that heat up rapidly, which can cause vertical stringing in the less than ideal conditions found within their stocks. And while they maybe built to endure periods of rapid fire, govt that issued them weren't that concerned with preventing the accelerated throat and barrel wear associated with pounding full power rounds through one in rapid succession.