Going on 1500 rounds through my Gen 4 G17 without an issue. Both my Gen 4's have been solid from day one. I rank them up there with my old Gen 2 G21.
-Glock Gen 4 G17/G19/G30/G42; Gen 3 G17/G34
-Sig P220ED/226 Navy/226 TacOps/227 SAS/229R/M11-A1D/1911 TACOPS/M400/556xi/HK VP9/XDM 45/XDs 4.0 45/Walther PPX/C39 AK47/RPK47/SLR 107FR