Does anyone know if it's possible to convert a RIA 2011 A2 GI HC .45 ACP into a 9mm if I change the upper? Also, if I change the upper will it typically drop-in or will it definitely need fitting?

Hey guys, I'm converting a few 45acp frames (one for me and one for a buddy) to host 9mm uppers. Both frames are ramped (his is Springfield Champion Loaded, mine is a Pantera 2011). So I am wondering if I could use one ejector to work with both calibers? I was looking at this one: Extended...

I know...it's a PITA but the 9mm is not readily available. SPS Pantera Series - Firearms - SPS Pistols by Eagle Imports, Inc. If the breechface is removable, can it easily be done with: Wilson Nowlin 5" bull barrel chambered in 9mm New extractor New ejector New hammer spring New recoil spring...