So I just noticed that there's something odd going on at the barrel port in the slide of my 45. Not sure how well the photos depict this, but basically there's some raised sharp metal around the bottom edge. It looks as though the barrel has been jamming against it during operation/firing and pushing back the metal.
Even more oddly when I look at the business end of the gun, not down the hole but across it, the top edge of the barrel sticks slightly out of the slide, where the bottom is slightly recessed, thus angled. So I tested it and there's slop, slight movement of the barrel when fully shrouded by the slide. None of my others do this. They all also are perfectly even across the top, if not evenly recessed.
Perhaps the point where the guide rod connects to the barrel has worn and allowed this movement? I haven't shot the 45 in a while, the last time it performed fine though. Any thoughts?