After around 20,000 rounds, I started getting stovepipes and ftfs. Thought it was the mags and kept tossing ones I thought were bad aside. I was down to 3 I trusted out of 12. Finally installed a VQ extractor and ran about 700 rounds today through all the "bad" mags. No issues at all. I'm going to install one in my backup even though it has less than 5000 rounds through it and not had any issues. Did have a few duds, think I'll pull the firing pin and check it out.