I have a glock 35. It is a 40 cal and glock calls it a competition model or some such thing, longer slide, better trigger , adjustable sites. I have 357 sig and 9 X 19 barrels for it. I only change the barrel, not the extractor , the springs or even the magazines. I haven't shot the 357 Sig much but it functioned fine. Same with the thousands of rounds of 9mm, that is with the 40 cal mags. With the Sig barrel it is my favorite woods - great plains carry pistol.