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Old rifle conversions

yitbos92
I have a Mossin Nagat 7.62 x 54R rifle that I love. Problem is, when fired, the bullet tumbles and does not travel in a straight consistant line. Being 7.62mm is equal to .30, what I was wondering is if it would be possible to bore it out to a .306, or larger but still keep the 54r sized brass.

Now I also realize that the brass would be impossible to find. Is it done for?
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Comments

10 comments

Date Votes
  • MIKE WISKEY
    no, the barrel you have takes .312" dia. bullets you need a new barrel. the min. rebore would be to 8mm or .338 and there isn't that much 'meat' on a m/n

    edit-muzzle wear usualy will not cause a bullet to tumble, bad groups sure. I've seen m-1's from korea that would 'group' 3'(feet)0 yrds. but no tumbled bullets
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  • TRAP55
    Might also have excessive muzzle wear, counter boring is cheaper than a new barrel.
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  • yitbos92
    Mike, I had a "sheet metal" target (road sign) that I shot 5 rounds at, saw puffs of dirt all around the sign, but one hit directly in the middle. It was a full metal jacket round, and there was a perfect profile of the bullet in the sheet metal.

    Wasn't a round hole, it had the point, with the silhouette of the bullet perfectly punched through the sign. And that was at 50 yards. Only thing I could think of is it is tumbling. The rounds I have been using are around the same age as the gun from what I can tell too so they aren't hotter loads.
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  • TRAP55
    Is the ammo military surplus?
    Whats the headstamp?
    There were Mosins with .308 bores, and ammo made for them.
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  • yitbos92
    Interesting. The engravings are all filed off. I got it at an auction in Ohio and the seller said it was a 7.62.

    Looking down the bore of the barrel too, it looks clean and the rifling looks crisp. So maybe it is a .308?
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  • TRAP55
    US and Russian "7.62" differ by about .003-.004. .308 bullets down a Russian .310-.312 bore will still hit inside a 10" circle at 75yrds, and not keyhole.
    My best guess is the muzzle is excessively worn from aggressive use of a cleaning rod by a Russian farmer/soldier. Russian armory's dealt with that by counter boring a few inches of the muzzle bore, eliminating the bad rifling.
    It would be a good idea to slug your bore and see what you have.
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  • jonk
    Keyholes to me suggest either a rotten bullet/powder combo in the extreme, or more likely, a mix of a very worn muzzle and oversized bore. Some mosins have bores up to .318" in diameter across the grooves. Even with a proper .311" bullet, that's likely gonna cause a problem. Could also be a very pitted/worn bore.

    The cheapest route would be counterboring, followed by replacing with a military take off barrel. My smith charges $50 to spin off an old barrel and put a new one on and check headspace. Reboring would cost a lot, and would get you into wildcat cartridges with expensive reamers such as the 8X54R and factory 8X56R.

    OTOH if you want to buy a new barrel blank and have it fit to the action, they can be made to feed .348 Winchester ok, or of course the original caliber.
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  • yitbos92
    Like I had said before though, the bore is mirror smooth, no pits scars or pock marks, and the rifling is crisp. I am wondering if it was a 7.62 at all or if it did get bore out and re-rifled to a larger caliber.
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  • torosapo
    There is a guy on the auction side that sells Mosin Nagant heavy target barrels.
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  • andrewsw16
    Looks like the key to your questions is more data. Slug the barrel and also make a casting of the chamber. The two will give you the answer. You just MAY be shooting the wrong cartridge. Good luck.
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