A couple or few weeks ago, I was at the indoor range, and I noticed as I was loading a couple of my 17-round Korean Glock magazines that something was odd. The feed lips weren't holding the cases very well at the front. Wasn't long before a bullet jammed against the barrel hood instead of going into the chamber. The feed lips had spread out.
I guess I'm not really surprised that the mags failed, just a little disappointed. My first post about the Korean magazines was back in 2010, so I would bet that each of these magazines has well over a thousand rounds through them. They have been my primary range mags for years.
