Slugged bore measurement Mosin Nagant 91 30 (.312-.300)


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U.S.SFC_RET
January 23, 2007, 08:59 PM
I recently purchased a repro sniper at a gunshow and slugged the bore. The Bolt matches the Barrel and the Buttplate and the Magazine but there is no serial number next to the woodline. The grooves measured .312 and the lands measured .300 thousands of an inch. First of all is this typical of this type of 1942 round receiver Ishevsk? Did they rebore the barrel? The tip of the bore grooves at the muzzle also measured .312 is the muzzle counterbored? It doesn't look counterbored to me but what do I know about Mosin Nagants? Can I expect this gun to be fairly accurate once I sight it in and can I expect it to increase in value in twenty years time?

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Vaarok
January 23, 2007, 09:47 PM
Sounds normal. Mosins can have bores between .308 and .314 depending on machining and wear, usually they're .311 or .312 diameter.

As a repro, don't hold your breath on value skyrocketing any time soon, since they're imported and faked-up in large numbers and quite popular, but I doubt you'll ever be unable to get your money back out of it.

Counterboring is where they recess the muzzle crown a half inch or more into the barrel by essentially putting a drill into the end of the barrel. If your muzzle isn't obviously a good eighth of an inch wider than the width of a bullet at the end, you're not counterbored. Given you've got a repro, and repros are built on the cleanest sharpest-bore non-counterbored rifles, you certainly are not counterbored.

U.S.SFC_RET
January 23, 2007, 09:52 PM
I am not counterbored then. I wonder If I could polish the bore a bit for the accuracy dept. Also I realize that this gun isn't an investment but a plinker.

rockstar.esq
January 24, 2007, 12:55 AM
Gotta tell you that polishing a bore thats likely shot well over 1000 rounds through it is mostly pointless. If you're a handloader you could load .310 bullets which are often labeled as ".303 British" which might help with the accuracy.
If you're looking for reloadable 7.62X54R Brass you might check out Wolfs gold line and or Winchesters white box.

grimjaw
January 24, 2007, 01:49 AM
I don't expect to make any money on mine, and probably a loss if I sell it. I've used a few tips to try tighten up groups, which already weren't bad.

These are the best strings I've posted with factory ammo.

http://www.grimjaw.net/mig/albums/theboomgoesthere/mixed/mosin9130_target-3.jpg

Since then I've sanded the barrel channel out to remove as much wood/metal contact as possible, and added metal shims to raise the gun in the stock. Also added a shim to the trigger group to lower pull weight and travel before break. Neither of those cost much money or time. I've considered having no more than an inch removed from the barrel while still leaving the front sight in place. The rifling near the muzzle isn't the best, and I figure removing that part + recrowning could help. I haven't had it out to the range though since I did my first alterations, so I'll try that before I start doing more permanent work.

You will probably see more consistent groups with commercial ammunition or rolling your own. I don't shoot much commercial and don't reload, so I take when I can get out of surplus. :rolleyes:

jm

Cosmoline
January 24, 2007, 03:12 AM
Yes, there are much easier ways to improve accuracy before you get into the bore. If the crown is good and the lands reasonably sharp don't mess with it. Concentrate on shimming and clearing wood on the inside of the stock. An aftermarket ball trigger can make an enormous difference as well.

U.S.SFC_RET
January 24, 2007, 06:16 AM
The trigger pull is excellent, one of the finest trigger pulls I have ever experienced in any milsurp and was pleasantly surprized. The crown looks to have been redone and I will shim the receiver.

dfaugh
January 24, 2007, 09:14 AM
You will probably see more consistent groups with commercial ammunition or rolling your own. I don't shoot much commercial and don't reload, so I take when I can get out of surplus.

Yeah, i gave up on attaining any find of real accuracy with milsurp ammo, some time ago. Before you go off do alot of work on it, get some decent ammo, and try it. You may be pleasantly surprised. I've found S&B to be pretty decent stuff, and not much more expensive than surplus.

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