Rock-n-Glock gave em a killer deal on a threaded Accu-Match .45ACP barrel for my trusty G21. I drilled out an Accu-Match .400 Cor-Bon compensator that I had laying around and it works fine on the .45 barrel. I'm shooting 45 Super out of it and will load up some .450SMC, as soon as the brass is available.
I use an extended, ported Federal barrel for shooting .400 Cor-Bon out of my G30. Never had a misfeed. One caveat: You can't use your G30 mag. You have to use a Klintonista G21 mag, for firing the bottlenecks. (That goes for the G30 and the G21.)