Problems with plain base checks

[MGySgt]

Problem 1. Anyone have problems with pain base checks staying on when you shoot them? I loaded 20 rounds with plain base check in a known boolit and charge of Unique. 50 yard group was over 6 inches and I found plain base checks on the ground 10 -15 feet in front of the shooting bench.

Note: I had but the checks on boolits that have already been sized and lubed.

Problem 2. The checks I seated on the boolits day after I made them no problem with putting them on in my RCBS LAM II. However when I checked some 6-8 weeks later there was a problem getting them into my sizer die. They seemed to be springing out on the bottom.

[popper]

Cu or Al GC? Probably need annealing.

[MGySgt]

Aluminum, soda cans.

[26Charlie]

Master Guns, I've been around awhile. I learned 8-man squad drill as a Jr.PLC at Camp Uphur from Sgts E-4. Trained on the BAR, a wonderful rifle, which the M14 on full auto could never match. Went to an artillery batallion which had a 4.2 inch mortar battery as well as 105 mm and 155mm howitzers. But - there seems to be a hole in my CB education. I think you are talking about using gas checks you cut out of thin aluminum with a die set. But are they to go on bullets not designed with a gas checks shank? An otherwise plain base bullet?

[MGySgt]

26Charlie, they are cut in a tool to be placed/crimped on a plain base boolit to create a stronger base for the boolit.

What that does is it allows a higher chamber pressure which in turn allows a higher velocity with a softer alloy. Inturn the higher velocity with good accuracy with a softer alloy and allows the boolit to mushroom thus a greater wound cavity. Yes you can get a higher velocity with a harder alloy, but they tend to be brittle and can/will shatter on heavy bone, like using lineotype.
Normal boolits that take copper gas checks will get you the same results but the factory gas checks are getting expensive and for the 357 mag I would want a new mold for the 357.

Plain base checks have been around for over 30 years. The normal metal for plain base checks is your soda/beer cans.

Semper Fi Brother

[SiliconeSword]

I've experienced the same thing and I think it's because the gas checks spring back because they're quite hard, so they're not on as well as you think. I've been annealing my cans and flashing in a toaster oven at full temp and they seem more secure, and I imagine are still much harder than any lead alloy we'd be using

[MGySgt]

How long do you bake your cans?
It makes sense that they are too hard and they spring back/grow.

I am sure others will chime in with their experiences

[JonB_in_Glencoe]

I have successfully installed PB GC on a bullet cast with a soft alloy, like 9 BHN or less. I use Lyman 45, and they stay on.
I have had problems like yours, with alloy harder than 10 BHN.

[MGySgt]

Interesting JonB

[GregLaROCHE]

I’ve always wondered how you could put GCs on plain bases, but I guess it must work, because a lot of people are doing it. I guess if the alloy is soft enough and you size afterwards, a portion of the alloy gets displaced under the GC.