Chuck. Nope, have not fired any rounds throughs the MPX with my major loads yet. It is is a very healthy round though. Around 172-175 out of the Open pistol. I wouldn't consider shooting it out of a blowback because, well, 185+ PF doesn't sound like a whole lot of fun or particularly healthy for a blowback ? , but my MPX sees much less gain in velocity over my pistol and is way softer at any given PF. I'm not inclined to mess with it at all though unless there is some competitive advantage to shooting big boy rounds. Max clearly makes the point though that the 140ish PF I normally run out of the MPX will get a spinner over quickly enough if I do my part. Big if, but still... You are right though. Lets see someone say the comp doesn't work on a PCC with that ammo!!
David, I think the weapon would be fine at major PF. I know a local shooter (and he is here on BE) who has shot 15K plus out of an MPX at around 165 power factor with no ill effect.