I've had two range sessions with the 42 now and run about 400 rounds thru it. 100 of which where Speer LE Gold Dot 90gr JHP. Hers what I posted on another forum about it. I really do seem to think the Gold Dots might just barely be catching the slide stop lever. For me it always seems to happen after the first shot with 5 remaining in the mag. Both mags...
Well I got back out to the range today.
Shot:
50rds Fiocchi 95gr FMJ
50rds PMC 95gr FMJ
50rds Independence 95gr FMJ
25rds Hornady CD 90gr JHP
50rds Speer Gold Dot 90gr JHP
The FMJs were almost flawless had one FTF followed by another, but the 2nd may have been operator induced. The Hornady went down range without issue as well. This brings me back to the Speer GD rounds. First mag was fine and then I started having the issue with it shooting the first round and then locking the slide back with 5 still in the mag. Happened 5-6 times and then the last two mags went thru with no issue. I tried both mags and the issue happened on both. After getting home, I did a field strip, clean and lube and everything looked ok. I looked at numerous things and one thing that stood out is that the slide stop lever tab protrudes into the mag deeper and has a different shape than both my 26/19 and 23. On those three the rear edge is angled and on the 42 it's not. It's a 90* angle. So I got to wondering if somehow the nose of the bullet could be just barely catching the edge of the lever and flipping it up. If you notice on loading, the bullets stagger slightly. Evens to the right and odds to the left. As I am out of Gold Dots, I did some testing with what I had. Pushing down on the 5th bullet with a Hornady CD was barely able to touch the lever. Of course the CD round is much narrower than the Gold Dot. I'm beginning to think that as the slide cycles back after that first shot, the next bullet is pushed down as the slide passes over, it shifts left slightly, and just catches the edge of the lever. This is just enough to flip it up and lock the slide. There does appear to be some evidence of contact on the edge of the lever. I've called and left a message with Glock and will see what they say. I'm thinking that beveling the edge might cure it. Let you know.