I agree with Stallones. I use PB with claybuster 1 oz. of shot for my 12g. loads and get 5100 psi that works summer and winter. I use Gun Club hulls because they are thinner than the STS so less goes into the forcing cone.
I have cut STS down to 2 1/2" and used the Harten crimp which is simply loading like a 2 3/4 inch hull so no changes are necessary for the loader but use an overshot 20g. card to keep everything in. The original crimp is still there. When you look at the front of the shell you see a circle left open and the overshot card which you can mark or color for different loads. Everyone thinks it is hysterical when you fire these shells and confetti comes out of the gun.
