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Bore size

Discussion in 'The Powder Keg' started by Snakebite, Jun 3, 2002.

  1. I have read a lot of different things about the bore size on the Mosins. Some people say its .312 and others say its .308. I just did a little experiment and took a 7.62 round and gently placed it in the muzzle end of all my guns. The bullet will go all the way in the muzzle of the 91/30 and only stops when the case hits the muzzle. Its a sloppy fit. Two other guns allow the bullet to go almost all the way in before any resistance can be felt and my latest M44 will only let the bullet go in about 3/4 of the bullet length before it stops. Thats the same as my SKS. Is there that much difference in bore sizes on these guns? My 91/30 isnt that accurate so maybe its just worn out. What is the correct diameter of these?
  2. Calvin

    Calvin G&G Enthusiast

    The only way to find out the bore size is to slug the barrel with a lead slug. I have owned several Nagants and have found that some have .308 bores, but most were in the .310-.311 inch range. If your 91/30 takes the .308 bullet all of the way to the case mouth with some slop, your barrel may be really worn out. Try slugging your barrel to find out what the actual bore size is, and go from there. HTH

  3. Big Dog

    Big Dog Retired IT Dinosaur Wrangler Forum Contributor

    I've read similar posts on various forums, and it seems there are variances in the actual bore size from one Mosin to another. Generally it is suggested to "slug" the bore to find it's actual size and determine if a certain bullet would be a loose fit or not. I have read of guys reloading with .308 bullets and having good accuracy, others have bad accuracy from too small a bullet for the bore.
  4. I agree I have found that different mosin rifles like different bullet dia. I shoot .311 in my 91/30's and my m44's seem to do best with .308.
  5. toolman

    toolman Resident Sasquatch Forum Contributor

    hey there,snakebite.most reports i've seen show an avg. of .311 ,+or- far as the 91/30,keep in mind that a lot of these guns had counter-bored barrels,so the actual bore size doesn't start until you get 1/2 in. or so from the muzzle.mine is the same way but shoots in the 2" to 2 1/2" range with wolf fmj ammo.