45 colt 300 grain swc gc

[pluger33]

I have recently gotten a rcbs .452 300 grain gas check mold, and have been having trouble seating the gas checks. I have been staring them by hand, then running them through my sizer, but most have not been coming out flush, and some wont stay on at all. Wondering if anyone has any helpful advise. Also, any info on powders and loads for this bullet (or useful references, my lyman, and speer manuals have nothing) would be greatly apreciated.

[Dale53]

pluger33;
It would be most helpful if we knew what sizer you are using. The different sizers require or benefit from somewhat different techniques.

As an example, when I use my Lyman luber/sizer, I use their gas check seater and seat all of my gas checks first, THEN go back over them again and size and lube them. The "gas check seater" as furnished by Lyman restricts the stroke on the sizer allowing you to set the check in the sizing die depression them seating the bullet firmly in the check. This works fine with "normal" size checks to checks that are slightly too tight for easy seating.

I have also, on occasion, found gas checks that are too loose after seated. That is simply a size problem and really calls for either slightly larger gas check shank (can be had by "Beagling" your mould, or using another bullet design). The other alternative is to try another brand of checks - they do vary in size, from brand to brand.

I have also used the Lee "push through" sizer. I seat the checks separately, then push the bullets through base first to secure the checks and size the bullets. It is quite helpful to pan lube the bullets after seating the checks and before sizing.

I found that the Lyman luber/sizer does such a good job with gas checks that I now use it for all gas checked bullets. It requires doing things twice (seating the checks THEN sizing/lubing) but does such an excellent job that I am happy to take the extra time.

For the record, I have a Star luber/sizer that I use with all my plain base bullets (except the long, soft bullets for Black Powder Cartridge Rifles - they get the Lee push through treatment after pan lubing).

FWIW
Dale53

FWIW
Dale53

[pluger33]

Thanks, its accually the rcbs lubrisizer i'm using. It seems like the checks are too small, or or not flared enough. I may have to try another brand.

[georgewxxx]

Tolerances of some mould and gas check making companies don't always jive. I've got several different sizes of old Speer gas checks almost all of the are undersized. The problem with the base being too big sometimes can be from the alloy your using too. Usually the harder your alloy the bigger your boolit will be.

You're working with .45 so you can't go to the next size bigger check like you can with a lot of smaller calibers. The one thing I do if I don't have too many rounds to load is, take a big round steel ball, mine is 1.24", and set it inside the gas check and tap it a few times with a plastic mallet to flair out the sides. It takes a few wackes to get the hang of it as how much force you need to spread the check. Large marbles need a plastic or leather mallet to keep them from cracking. The back side of a ball pien hammer works too but is a bit clumsy. ....Geo

[pluger33]

Thanks much I will give it a try.