Thanks for the suggestions. I have settled on the Octane 45. I know its not as "quiet" as a 9mm can but I also have a 45 and SW40 that I would like to be able to use the can on. I also figured the slightly larger bore will reduce the back pressure on the 9mm blowback upper. Still don't have the NFA approval in hand for the MG but hope to get out to AGC to play soon.