I can't answer your question, but in regards to function, there's no reason why the Gen4 wouldn't handle the .45 Super. Underwoods offers some .45 Super and says that it can be shot in the G21 but should have stiffer springs, and the Gen4 does have a stiffer spring than regular Gen3's. I would personally rather have a better supported barrel as well, but I'm not going to say it's a must because I don't know, I've only loaded .45 Super for use in my KKM barrel.
"Condemnation without investigation is the height of ignorance."
Last edited by SDGlock23; 10-08-2012 at 16:54..