I recently added a NY-1 spring to my G37 Gen3, and decided to give the gun a thorough range test. I ran 3 mags of 200gr. Speer Gold Dot through the gun (3 newly-purchased mags). Zero issues. I then ran 90 rounds of Speer 200gr. Lawman through my "range" mags (3 older mags, 3x each). I had three malfunctions, each identical, involving two of the magazines. The last round in the mag stood up almost straight (slight forward angle) and wedged against the barrel hood. On the third malfunction, the last LIVE round in the mag actually EXITED the ejection port when the previous casing was ejected. I then retrieved my three newer mags from my range bag and candy-caned them with 200gr. Gold Dot and 200gr. Lawman. No issues! The obvious answer is that the three older magazines are somehow out-of-spec. They've met concrete since I've had the gun, and were already dinged-up when I bought the (LE trade) G37. However, I did a post-mortem on the three mags and found no apparent damage to the feed lips. The springs in each magazine are the proper 11-coil springs, and EASILY pass the two-coil test (more like four coils protruding). The followers also appeared undamaged. Has ANYONE seen this before? I can certainly send the mags back to Glock for analysis, but I'm genuinely curious. And, like I said, the gun didn't malfunction with any of the three new G37 mags I purchased. The followers are identical in the newer magazines. Your responses are appreciated!!!