Aluminum check on 7.62x54r ??????

[tomme boy]

OK, I have a bunch of al. checks that I am using on my 308win rifle. I am also reloading for 2 Mosin Nagant rifles. They both need to be sized at 0.314" Now here is where I think I might run into a problem with the al. checks. When they are sized to 0.314", the check is at 0.311" and the rest of the boolit is 0.314".

Now do you think this is going to cause any problems, or will the check bump up upon firing?

I am thinking I need some thicker checks to take up the difference. The shank on the boolits are the same as on 308 win. boolits. 0.284" So the 0.014" al. checks don't have enough thickness for the larger boolit. Am I right on this?

[MUSTANG]

TommeBoy:


Shank: .284 + .014 + .014 = .312


60912

Depending on the aluminum (dead soft to hard) you will get some level of spring back at the upper edge of the cup. So it may actually go larger than the .312 dimension from the attached drawing/your figures. When I measure my sized .308 cast bullets that are sized to .310, .311, or .312 I see spring back where the top of the cup is slightly larger than the sized lead driving bands due spring back of the Amerimax Flashing (.014 thickness) I use for Gas Checks. This does not seem to be a problem, once sized to my RCBS, Lyman, and NOE boolits the only way I can get them off is to melt them.


I would seat the gas checks, Size them and see what you get and how the groups work out. Keep in mind, some gas check types do shed in flight by design.

Mustang


P.S.

I just measured 10 unseated gas .30 cal Aluminum Gas checks from my stores, and each was .314 across at the top upper edge of the cup (before seating on Boolits and sizing).

Mustang

[tomme boy]

I am getting 0.311" right now. I am thinking I am going to have to buy a check maker for the 0.314" with thicker al. Or, I am going to have to use Hornady. They are at 0.314" and are very tight. The alum. ones are loose. I can flick them right off.

[TreeKiller]

What kind of checkmaker? If it is Pat's send him a note and he will send you a new male die part to form the check bigger. He made one for me for the 303 and 7.62 X54R.

[tomme boy]

That will not work. You have to have thicker material. The problem is the base of the bullet is 0.284". So with the check at a max of 0.014" x 2 + 0.284= 0.312 If the base was 0.286" then the mandrel you are talking about would work. But since it is not, then the checks should just fall off.

[MUSTANG]

Tomme Boy:

I have read in the past that some shooters have sandwiched gas checks (one stacked inside of the other). In your case, the theory for this application would be to place a check made from Coke Can side material (~ .0045) onto the base; then atop that check place a .014 check. Since the top of the check is wider than the base; it would slide past the Coke Can base and expand as it was pressed on, then the side would grab the check underneath. The sizing die then sizes the expanded check to whatever the sizer die is.

I have never done this, and as I recall the posters on this idea still had gas checks shed in flight, which they were attempting to correct. Provided as a thought if you are trying to avoid procuring an additional check maker. Anyway, there was a lot of activity in this area on this site back in the 2005 to 2010 period, you might want to research the old postings.

Mustang