I just necked down and fireformed 200 pieces of Alpha 6GT to 22GT. I used a .249 diameter bushing in a 6GT Redding type S bushing die. It leaves a small ring at the neck shoulder junction but that did not affect chambering. I "fireformed" with light charges and 75gr BTHP's. The brass came out beautiful. The necks will be extremely long so prepare for a serious amount of trimming once you're done. I believe the 6GT after firing was about .020" longer than factory 22GT brass after necking down and firing.