Glock Builder

I had a similar problem with one of my builds. After stripping it down and checking each component's mating to each other, and substituting 'known good' parts, I was able to isolate the problem. In my case, it was a machined part I had purchased from a reputable manufacturer. The barrel was machined too tight for my build, but was within standards. Most likely with parts from different manufacturers, tolerances start stacking. I swapped the barrel with a similar one and she works like a dream. Hope that helps.