I just picked up a Gen 2 Glock 19. Today was the first trip to the range with it. I was shooting Federal American Eagle 115gr. Out of 220 rounds, I had a couple of stovepipes, which I attributed to being new to the Glock. The last 50 or so rounds had a couple more, and really weak ejection. I mean the shells were basically "dribbling" out. It was also shooting about 3 inches lower than it was earlier. Does this sound like it was probably just a bad box of ammo, or something worse?