If you want a 1911 style .22 for steel challenge, build it on a 2011 frame. The reason is that the magazines for the 2011 frames are far superior. There are just 2-3 companies making them and they are very uniform in design and specifications. There are a lot variations of the old Colt Ace magazines out there as well as newer polymer magazines for the 1911 conversions and the result is FUBAR. The guns do not feed reliably enough for steel challenge. For plinking, sure. For hunting, sure. For Bullseye competition, eeeeeh ... maybe sometimes. For steel challenge absolutely not. I have had built guns on both platforms and I will sell my Marvel and Colt 1911 .22 magazines if you want them. I run a 2011 .22 now and it actually RUNS.