Joejoe05--I have not had this problem myself but I may be able to ask a few questions and possibly help.
Is it possible that the slide is not going far enough to the rear on recoil to allow the sear to catch the hammer notch on recoil? If so, you should look for the reason for the limited slide movement. The usual suspect is the ammo. Are you using 130 PF min match reloaded ammo or factory box ammo? What weight bullet? How far are the casings landing from your feet when shooting standing still? With a 13 and 11 springs, slow slide movement is not likely to be a problem. Violently hitting the rear stop is more likely, possibly resulting in some sear bounce. Lots of folks use the weak springs for run and gun matches, however, but with light reloads, not so much with factory ammo. You could check this simply by going to a 13 or 15 lb recoil spring, which you could get quickly from wolff springs.
Have you made any changes to the pistol or to your grip corresponding to the start of the hammer follow? Any chance you are slowing the slide dragging a thumb on the side of the slide, for example? Is the slide stop down all the way and not dragging on the slide until the magazine is empty?
It may be that a combination of factory ammo and light springs has shown up as the gun got a little looser from new. If so, heavier springs or lighter loaded ammo may fix it. If you are using hot factory ammo, like a self defense round, try some Remington UMC 115 FMJ ammo if you can find it and see if the problem persists. It is lower velocity than most and you will feel the difference.
Call CZ Custom on Monday and tell them about the problem and what ammo you are using. They may send you some springs or at least tell you what to change to IF they think that will solve your problem.
So, that is all that I can come up with as far as ideas for a problem that I haven't had to deal with myself. I bet you will some hopefully more helpful suggestions later today.
Joe
