Re: Ackley fireforming question
I fire form 257 Roberts Ackley Improved from 257 Roberts brass, 10 gr of any pistol powder, back fill with instant cream of wheat, and if to be fired horizontally at the range, then I put Ivory soap in the case mouth to seal in the cream of wheat.
I got the cream of wheat sales job from famous [or infamous] gunsmith Jack Belk on AR forum, before he got bursitis in his shoulder and went off line.
If you plug that load into Bart Bobbitt's [another guy I have lost track of] formula for barrel wear for your cartridge, you will see it is a small fraction of the wear of normal load.