mosin optimum barrel length


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Psyco Tyco
November 20, 2010, 10:05 PM
alright ive looked around for an answer but havent found consistent results.

i want to shorten the barrel of one of my mosins (dont worry it was all non matching numbers a missin sight post and had an ati bolt conversion when i bought it and bought it soley for modding further...btw it was only 30 bucks at the pawn shop)

its a 91/30 with a 28 3/4" barrel and 2 1/4ish inches of counterboring. but i want to remove as much length from it as possible while still burning all the powder from the round. ive heard the 7.62x54r compared to the 7.62 nato and a .30-06 with answers saying 18 inches is long enough and others saying 22 is required...what would yall recommend as the minimum barrel length

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Carl N. Brown
November 20, 2010, 10:36 PM
In Mosins, I have both a 91/30 and a Type 53 carbine ~20" barrel; personally I would not go shorter than 20", just from keeping enough weight to dampen recoil and barrel length to reduce muzzleblast. I have gone walking through the woods on a snowy evening with the carbine and it seemed handy but I suspect I would not notice any difference with the full length barrel, unless I went off trail through the brush.

Your problem though is over 2" counterbored at the muzzle, probably due to worn/corroded barrel. With a noncollectible gun, function is more important than form, so whatever barrel length gives you a good solid muzzle is important.

Psyco Tyco
November 20, 2010, 10:55 PM
so for argument sake say this is a brush gun set to replace a single shot sluggun on day hikes and im getting a muzzle break for it. 20 inches would give adequate burn or would i be able to take that extra 2 inches off and still have full burn

Sunray
November 21, 2010, 12:46 AM
"...while still burning all the powder..." Barrel length has little or nothing to do with that. The powder is totally burned in the case. Does have to do with velocity, muzzle flash and blast. An MB will increase the noise for the shooter and everyone around him. Wouldn't let that bother me though.
The M44(8.9 lbs. vs the 9.5 lbs you have now.) has a 20" barrel. Well known for impressive felt recoil, muzzle blast and flash. So does an 18" .30-06 or .308.
"...probably due to worn/corroded barrel..." Very likely. I think I'd start by lopping that off and crowning. For $30, you can afford to play with it if you find you don't like a 26" barrel. Wouldn't go to 20" myself. 22" would do nicely.
You can work up a load using 123/125 grain bullets made for the 7.62 x 39 too. Same diameter. There's 125 grain SP data on Hodgdon's site. Close enough for 123's. Two grains won't matter.

rcmodel
November 21, 2010, 01:07 PM
Peronally, I would not go less then 20"-22", and I most certainly wouldn't put a muzzle brake on it.

The sharp muzzle blast hurts far worse and does more bodily harm then the recoil.
I doubt you will be wearing hearing protection while hunting or hiking.

rc

OC_
November 23, 2010, 12:30 AM
I have a PSL thats cut down to 20", i kinda regret taking it that far but i get fantastic groupings so i cant complain. Though, that's probably due to the target crown. I also have one of those linear brakes that directs the blast down range. It works very well when im not shooting under a tin roof in keeping the sound down.

Anyway, it if you consult this chart (http://7.62x54r.net/MosinID/MosinAmmo001.htm) you can see that there is about a 200fps loss between the M44 with a 20" barrel and the M91/30 with a 28" barrel using 80's russian surplus. The Finnish M91 with a 31" barrel was only 60fps faster, which would suggest that the loadings become inefficient after 28".

I don't think i would go below 20", and I think the PSL had it right at about 25" from the factory.

kaferhaus
November 23, 2010, 05:39 PM
Barrel length has little or nothing to do with that. The powder is totally burned in the case.

Might wanna check that... just saying

Muzzle flash requires both fuel and oxygen The only fuel to burn is what?

In fact the bullet starts moving at primer ignition, the bullet is already in the bore before the powder is fully consumed.

The bullet's obturation, (sealing) of the bore is one of the things that allows pressure to build thus the energy spikes to propel the projectile out of the bore.

Of course it all happens in a nano second.

Chamber pressure is not linear, there's a short spike (primer ignition beginning of powder ignition), followed by a huge spike (obturation), a sharp downward spike followed by a shallow dive to zero as the bullet exits.

ball3006
November 23, 2010, 10:28 PM
have different burn times. A shorter barrel needs a faster burning powder to completely burn up before the bullet leaves the muzzle. For example, I have a Thompson Contender in 223 with a 10 inch barrel. If I shoot factory loads, there is a great muzzle flash from the unburnt powder. I reload with H322 and there is no muzzle flash at all. The 7.62x54r cartridge was developed for the Mosin Nagant M91 which has a real long barrel. That is why you get a terrific muzzle flash shooting surplus ammo out of a M44 or M38. As posted above, trim the barrel back a little at a time until you find a length you like and shoots accurately....chris3

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