Some case forming notes from real experience...
During 22 Mamba forming die development, it was discovered by George, that 223 parent brass, with the extra thickness around the shoulder and neck area when forming the short cases, did not want to form the 30º shoulder. It was crush city.
So with much experimentation, George discovered that if he set the 223 Short die with its 23º shoulder, 2 1/2 turns off the shell holder and formed the case, then changed to the 22 Mamba die with its 30º shoulder, set normally, and finished the case forming, cases formed without losses.
Also in George's own words: "Now 1 more thing AR's are notorious for swelling and pushing the shoulder forward during the firing cycle. I intentionally made it where you have to do a little extra cam-over on the press to do a full shoulder bump.
You can play with this using your case gauge as a reference. Reason being is I didn't want to have to make you 2 dies for the bolt gun and AR or overwork the brass all the time just to keep the AR happy."
It is possible I will be at the range next week to finish 223 Short 100 yard tests and fire forming 100 22 Mamba cases using 5.4gr of TiteGroup. George says that while that load may not be the be-all and end-all of case forming, I can work up from this load to more potent loads using L'Il Gun once cases are basically formed.
I will publish data on the final case capacity comparisons across many brands compared to 223 Short case capacities when 22 Mamba fire forming is done.