Haven’t seen this kind of failure before. This is an EGW flat wire recoil spring retainer from my carry gun. Luckily I have several of these things floating around. Never hurts to go over your gun after you are done shooting it.
Jeez, that's.. hmm. The fact that the guide thingimies (if there's a name for that I don't know it) are intact and seemingly unbent, but the rear appears to be blown outward, would lead me to believe that somehow the retaining wall slipped past the guide rod and then got slammed by it. I'm not exactly sure how that happens though. Well, either that or just really bad metallurgy against the force of the recoil spring.. but I dunno.
my guess is it would have failed on the next mag full.
It is steel. It is a EGW flat wire guide rode assembly for my Kimber Ultra carry 2 slide on one of my builds. My guess is the spring didn’t slow the slide down enough when pushing out the HD rounds and it slammed the fully compressed spring hard enough to damage the retainer. A 150 rounds and more than a few mag fulls of Plus P stuff probably was all it could handle. I put a replacement 22 pound spring in and a replacement retainer in yesterday. I ordered some stock recoil assemblies from Kimber just in case.