1932 mosin 91/30 bore diameter

[Spawn-Inc]

so i just got said rifle and i slugged it (1" into the bore from the muzzle) and it came out to a whopping .315-.316 grove diameter, and .303 bore diameter.

what size cast bullet should be used and i assume .310-.312 for j word's?


thanks,
Robert.

[DangerousDrummer]

I use 312s just to be sure that the bullet is nice and tight. The PRVI ammo is 311, but the Hornady 312s group better than factory PRVI.

[khmer6]

You might want to look into paper patching with an oversized bore that big

[Larry Gibson]

Suggest you slug or cast the chamber neck, subtract twice the thickness of your case in the neck and subtract from the slug/cast diameter of the chamber neck. That will give you the largest cast you can load. Also slug the bore another 3 times running the slug from breach to muzzle.

If the measurement or the slug come out as large as the computed max diameter over .314 and you want to use regular cast bullets then a custom mould will be needed, beagling a mould, lapping a mould or sizing down a larger mould. I've had really good luck in such as yours with Lymans 8mm mould, 323470 (still commercially available) and some other designs can be sized, lubed and GC'd in a .325 H die (your set for 8x57s with that) and then sized through a honed out Lee sizer to what size your MN needs and can use. I sized them as far down as .314 with excellent results. I size them in Lee sizers at .314, .316 and .318. Pictured is a 323471 and a 190 gr GB 8mm sized from .325 down to .314 in the Lee sizer. Bullets must be lubed and GC'd before such sizing and you must consider the to fit of the nose in the throat. Most MNs have sufficient throat for such bullets.

Larry Gibson

74799

[hylander]

If your Mosin has not been counter bored, you need to slug it deeper.
The muzzle most likely just has excess wear.

[Multigunner]

The Finns used to make jacketed hunting bullets that would bump up to fill out bores up to .316.

The Hornady .312 150 gr has been exceptionally accurate in a number of Lee Enfields with over sized bores. It was designed for usein the 7.7 Jap but works great in all old milspec bores of similar diameters so long as theres any rifling left to speak of.

[Spawn-Inc]

thanks for all the help guys, i will run a slug all the way through and see if it changes.