Originally Posted by nickE10mm
But would the limitations to blowback (in a carbine) be any more serious than the limitations created by, say, a stock G20 barrel?
Probably not. :-) which means you should be able to wring more velocity out of the setup...
Actually, a lot. I've been down this road before with other cartridges. I'm looking forward to it, but it'll be a couple months before getting started.