I have a brand new Glock 20. The first time I fired it (after field stripping, cleaning and lubing), on the second magazine I fired I had a problem. It fired fine, extracted the casing, cycled the next round, but the trigger did not reset -- it remained fully back even after I released my finger. The trigger stayed all the way back until I racked the slide. In shooting it some more, it happened two more times. In those cases, I just pulled the slide back 1/4" or so, which reset the trigger (like you can do with a Glock when dry firing). I sent it off to Glock, they returned it saying it was inspected, test fired and no problem was found. I was shooting double tap ammo (can't remember what grain). Not sure if type of ammo would make a difference. Any ideas? It's hard to trust a gun that only works some of the time.