I’m sure this question has been asked lots of times before, so please indulge me. Is it true that you can’t convert a P320 9mm, .40,357 to a .45 ACP?
Machining the slide would be impractical as ypu would need to machine the breech face larger, along with the breech where the barrel locks up as well as the muzzle end of the slide. The slightest mistake would ruin the slide. Even when done it is likely to not work properly as the extractor was positioned for 9mm....I already did a build that way. You didn't mention the upper. Just in case some one was planning to do same thing I just bought it up. Although I wondered if there is a way to fit .45 cal barrel to a 9mm upper. It probably could be done with machining the slide. I doubt it would be practical and strength of slide could be compromised.