Can you do that? What about the ejector? If this is correct, I could put a 9MM upper on a 45, correct?
I'm shooting from the hip here. That may work going from a 45 to a nine. The ejector is different but the kicker may be that the feed ramp on the factory 9mm pistols may be different.
Figures don't lie, But Liars figure Assumption is the mother of mistakes