I bought a brand new, old stock K40. First few hundred rounds, it ran great. Then it started locking bag during a string of fire. I assumed it was my thumb. Tried left handed for awhile, still did it. I then looked at the bullet that should have chambered and found a ding on it that corresponded with the slide stop. Ordered a new slide stop. Same problem. Sent it to Kahr, new slide stop and a note that it was test fired and working properly.
No. Still doing it. Same ding on the bullet. Bought two brand new mags, still doing it, a lot. Like every 15 rounds or so. It's about to go back to Kahr. I'm convinced, something is out of alignment and, the rounds are just too close to the slide stop. There is very little room in there if everything is working right.
If they can't fix it or replace the pistol, I may just grind off the stop. I tried filing one down until it barely engaged the tab on the follower, and, it would still hit. I would rather the gun close on an empty chamber than stop on round 2-4-5 whatever.