Mosin Nagant bore slugging

[nhopper]

I'm a bit puzzled here. I slugged the bore and measured the resulting nub of lead. .3105. Now what? 308 bullets will work?

[Kraschenbirn]

If that .3105 is the major (groove) diameter, a .308 boolit is going to be considerably undersize. Most likely, you'll need something more like .312-.313 (or larger) to achieve an acceptable level of accuracy.

Bill

[nhopper]

When looking for cast boolits vs jacketed, does one need a larger diameter projectile in cast? Most of the military projectiles measure a .311 width. I know when I reload for pistol, most cast products are .001 wider than their jacketed or plated counterparts.

Now, knowing the correct diameter, how does one determine the necessity of gas checks and hardness? I'd be looking at something around 1600-1800 FPS in a 180-200 grain projectile.

.3105 was indeed the groove diameter.

[tomme boy]

.312-.314 would be ideal for the mosin in lead for your rifle. .311 or.312 in a jacketed bullet.

[leadman]

At the velocity you seek it would bnefit you to use gas checks. You probably will be able to use air cooled wheel-weights, but water quenching would help I believe.

Powders like 2400, SR4759, AA 5744 will give you the velocity and burn well.

[Ed in North Texas]

snip

Now, knowing the correct diameter, how does one determine the necessity of gas checks and hardness? I'd be looking at something around 1600-1800 FPS in a 180-200 grain projectile.

snip

The purpose of a gas check is to protect the base of the boolit from gas cutting. Gas cutting comes from the high pressure hot gases escaping past the base of a plain base (PB) boolit and contributes to leading the bore and reduced accuracy. Generally considered (or used to be) that gas checks are not needed for any boolit velocity less than 1400 feet per second (FPS). Obviously your boolit has to be designed for a gas check in order to put a gas check on the boolit.

Hope that helps.

Ed