I have SS guide rod assys and aftermarket springs in all 5 of my Glocks. The 2 G21's and G17 have Alchemy captive rods with ISMI flat wound springs. G19 has a Nowlin dual spring unit and the G30 has a Wolff 2 piece. There is slight wear on the barrel(after about 10,000 rounds) but not in the slide hole.