I have 3 of the KCI G17 mags. 2 would not drop free from my G17, so after a little looking I determined that it was the front to back dimension of the mags causing the problem. So I tweaked them in my vise (meaning squished them a little) and now they drop free fine. I've had them since Feb/March and have been using them in matches with no problems, in fact I used them for a 2 day pistol class (860 rds) a couple of weekends ago and they were fine. But, I'm not going to use them for Area 1 this year, I think they are fine for local matches, but for a "big" match I don't want to take the chance.
ETA: When I first got them, I accidentally dropped a fully loaded one on concrete and it broke the base pad. I have been running that mag with a spare Glock base pad with no problems.