I think you didn't put the recoil spring in all the way. They warned me about this when I got my Glocks. It has to be put all the way in on the barrel or it(spring) will hang low and damage reciver.
SHTF vs TEOTWAWKI you ask? SHTF, just some crap on the ceiling and walls, TEOTWAWKI end of the world as we know it. Orignally made by 9mm/®™©