So today, I'm at my department's range quals. Nothing real challenging, just empty our 3 mags (15rds each), plus chambered round, in the process of a couple drills that are POST-mandated for basic peace officer certification. We have to do this drill every year, I'm pretty sure. The gun is an issued Glock 22C with M3 light, .40 S&W, shooting Hornady TAP CQ and a couple Winchester Ranger-T (RA40T load) ammo. so it's 1 mag at 3 yards, one-handed, from the hip, 5 rounds at a time (well, the last one is 6 owing to the +1 round). Well, my slide is locking back about every other shot, sometimes every shot. I'm pretty damn sure I'm not limp-wristing, and I know I'm not touching the slide lock lever. Gun runs dry, reload, move back to 7 yards and shoot two-handed, same strings: 5 shots, 5 shots, 5 shots, reload from dry. Slide locks back prematurely a few more times, 3 or 4, and I know that 1 might be me, since I have a funky grip style, but the rest I'm sure aren't. Same thing happens when we move back to 15 yards after the reload, but only a couple times. After it's done and we're cleaning up brass, one of the rangemasters comes up to me and says "hey, what's up with your gun? kept messing up on you there." I say "dunno, I've never had that happen before, it just kept locking open even with rounds still in the mag." So he says "go over there when we finish picking up and have Greg look at it. something might be worn out or something like that." [Greg is the assistant armorer and one of the senior rangemasters for the department] So I go clean the pistol first, then go to Greg and say "hey, the other guy said to have you look at my weapon. wtf is going on?" Greg says "well, are you sure you're not limp-wristing? What's your grip like when two-handed?" I explain that my grip is a semi-IPSC-style thumbs forward grip, and I demonstrate to him, including my method of avoiding activating the slide lock. I also explain that I've never had a limp-wristing problem, even last month on a nearly identical course of fire with this same gun. so he decides to wring it out some. I've just refilled my mags with fresh duty ammo--Win. RA40T all the way--and he grabs a couple of my mags, then goes to the line for a test run. Two-handed, at 7, he has maybe one lockback. Then he goes to the 3, and one-handed. Premature lock city. Every round, sometimes every other, the gun locks open with ammo remaining in the mag. I'm like WTF, since this is my issued duty gun, and I'm supposed to trust my life to its reliable function. He's like WTF, too, since even He-Man the Range Master is having the same problem as The Kid. So he strips the gun, again. Thinks something's up with the slide lock/release lever's spring. thinks the lever itself might be a little off. Looks at the mags. Gen 7 and Gen 8 followers, pretty darn new. Looks at gun's serial number, decides it's pretty old, but shouldn't be that worn. then sees a problem. The locking block pin is snapped in two. Only one of those two is still in the gun. Greg says "well there's your problem. the lever bears some against this pin, probably without the left half of the pin, the lever's jumping around under recoil and sometimes just gets the timing right to catch the slide back." I say "oh great, my Glock is down. Now what? I've got to get back to work, and I have a gun that won't." So he replaced my busted-ass pin with the intact one from his duty pistol: he's a cool guy. Then he tells me that he's seen 7 or 8 other Glocks in the department exhibit the same problem recently. So I have a fixed Glock--which only broke through normal wear and tear--and all new duty ammo. I dumped another mag through it, from the hip and from a normal two-hands stance, and it worked fine. And it only took 45 minutes longer than a range should have. CLIFFS: Glock 22C locking back. Not limpwristing. Locking Block pin broken, probably from regular wear and tear. One of several in the department to have this problem lately. Pin replaced from armorer's personal gun. My gun works now, and I have all new ammo. Glocks aren't all that great.