Can you swap barrels up in the same caliber? For example, will a Glock 31 barrel fit & function in a Glock 32? I ask because I like the idea of a little more velocity in the compact line. Barrel lengths as advertised (4.49", etc.) don't mention that about .49" of that is chamber. I love the 23/32/19 size, but would like full-size muscle if possible. An alternative is a threaded barrel, which gives you a little more length, but not much. Maybe not enough to make a real velocity difference. Another interesting concept would be putting full-sized uppers on compact lowers, but that wouldn't actually work, would it? Finally (I'm hijacking my own thread ; ) it would be sweet if you could modify a G22 sized gun to work as a single stack .45, but I'm guessing that's impossible too... For me, the G21 is too fat, the G36 is too small, and the .45 GAP is... a .45 GAP. I'll be happy if some can answer the intra-caliber barrel swap questions. Thanks.