I just bought a new/used Kahr MK9. some guy sold it to my gunshop/smith without ever firing it, and my gunsmith put 2 or 3 mags through it with no problems. He was about to clean it and put it on the shelf when i came in. I got a good deal and took it home with me. When i cleaned it, it was NOT dirty at all! It still had the stuff from the factory on it(it was blue by the way, never saw that before). Its great except for the slide locks back every few shots! I called my gunsmith and told him that. He said he put a new stainless steel guide rod and springs in it and that i needed to break it in, and the recoil spring is probably too strong. No malfunctions of any kind, it just locks back. I've never had that problem before. Is my gun smith right and the recoil spring is to strong? I put some wolff springs and guide rod in the gun, and im hoping that will fix the problem. So my main question is, Is there a specific reason why the slide locks back? ammo? recoil spring? it happened with american eagle 115gr fmj and rem golden sabers 147gr. It happened with the flush mag and 3 of my 7 rounders. I am lucky and have a great gun shop/gunsmith and he's always honest and has good prices and doesnt lie to people so i know he will take care of me! I just like getting advice from more than one person.