Ok, my son just bought a Glock 23 Gen4/.40 I have shot it enough and so now I want to be a Glock owner. I own a Colt .45 1911 and I must say I like the heaver gun for that caliber. Here is what I have been thinking of buying. 1. G19 9mm since I already have the Colt .45 Now I was thinking about this a little more and I told my son I would buy him a KKM barrel (9mm) for his G23 as a gift. Upon thinking about this, I just came up with me buying a G?/Gen4 -.45 SINCE I already have a .45, then buying a KKM barrel in the 9mm so I can have both of which I really don't need both calibers since I have a .45 already. My thinking is I can have more range w/the G23 in barrel swaps than w/the G19. Am I right? Decisions, decisions. Also, will the spring for the slide need changing going from the .45 to the 9mm? Thanks, Jim Hope I made since. P.S. I will shoot the 9mm 65-70% of the time and still carry my 1911/to the range as well.