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I've been doing a little casting and want to do more. I've been thinking about adding gas checks to my 30cal Mauser Broomhandle boolets which I'm working up. My question now is why do I need a special mould to use gas checks? It seems to me that if you put the as-cast boolet in the gas check cap and squeeze it through a sizing die it is going to come out the right diameter regardless. Maybe a few thousandths longer to account for the lead displaced by the gas check collar but that shouldn't hurt anything as far as I can tell. Or am I missing something???

Gerry

Gyrogearhead wrote:I've been doing a little casting and want to do more. I've been thinking about adding gas checks to my 30cal Mauser Broomhandle boolets which I'm working up. My question now is why do I need a special mould to use gas checks? It seems to me that if you put the as-cast boolet in the gas check cap and squeeze it through a sizing die it is going to come out the right diameter regardless. Maybe a few thousandths longer to account for the lead displaced by the gas check collar but that shouldn't hurt anything as far as I can tell. Or am I missing something???

Gerry

Yeah, it will never work. The outer diameter of the gas check roughly the same as the OD of the bullet. The inner diameter of the gas check is the outer diameter minus twice the copper thickness. It will never fit on a bullet that does not have a reduced diameter shank to sit on. See the diagram below, The reduced diameter of the shank is smaller so that the gas check fits onto the bullet.

Jumping Frog wrote:

Gyrogearhead wrote:I've been doing a little casting and want to do more. I've been thinking about adding gas checks to my 30cal Mauser Broomhandle boolets which I'm working up. My question now is why do I need a special mould to use gas checks? It seems to me that if you put the as-cast boolet in the gas check cap and squeeze it through a sizing die it is going to come out the right diameter regardless. Maybe a few thousandths longer to account for the lead displaced by the gas check collar but that shouldn't hurt anything as far as I can tell. Or am I missing something???

Gerry

Yeah, it will never work. The outer diameter of the gas check roughly the same as the OD of the bullet. The inner diameter of the gas check is the outer diameter minus twice the copper thickness. It will never fit on a bullet that does not have a reduced diameter shank to sit on. See the diagram below, The reduced diameter of the shank is smaller so that the gas check fits onto the bullet.

Thanks for the note J.F.
You are absolutely right but I didn't give you enough information on my particular problem.

I was planning to use 32 cal gas checks. My broom handle Mauser takes a bullet .311 as it slugs at .310 -.3105. I was thinking about 32 cal gas checks as they would leave about 5 thousandths clearance all around the base of the bullet and should enter the sizer die without difficulty. Comming out the other side they would be a nice .311 diameter and firmly crimped to the bullet base, I think.

I haven't shot the pistol very much because I only have been able to obtain Russian Tokerev ammo which is identical in size to 30 Mauser factory ammo but is loaded a lot hotter, 1920 fps vs. 1400 fps for the Mauser. I've also read that a regular diet of Tokerev is usually fatal for a broom handle. The only reason I used it at all is that the larger bore in my pistol means there is a sizable gap between the 0.300" Tokerev bullet and the bottom of the 0.310" grooves. Lots of room for blow-by equals lower effective pressure. How much? Who knows but it can't be good for the bore or accuracy.

This is the problem; I've never used gas checks before and although my plan seems like it might work there is always the hidden glitch. Like what happens to the copper in the base disk of the gas check? It will be held in place by the flat base of the lead bullet and the flat face of the sizer ram while it is squeezed down in diameter but will it wrinkle up or bow up even under the pressure of the lead core's friction with the sizer die? And would that hurt anything?

I'm thinking I need to use gas checks as the normal velocity of the 30 Mauser pistol cartridge is 1000 - 1400 fps depending on how hot you want to load it. Factory was 1400 fps but my pistol is almost 100 years old and I don't want to go that high in pressure.

To date my cast bullet experience has all been with 45 ACP and everything has worked well so far but the increased chamber pressure of the 30 Mauser has me a little worried about possible bore leading problems. Any advice would be greatly appriciated.

Regards,

Gerry

Man, I'd hate to give you bad advice on that gun. Head over to the castboolits forum where you can get advice from the real experts, including people loading that round.

Thanks, J.F.

I'll go over there and troll for opinions. Hopefully there will be someone who has crossed this bridge before me.

Regards,

Gerry