I'm a new CZ owner and have had a used Gen 1, S/N A77--, 2010 model 40 caliber pistol since last fall and am just finishing upgrading it. Major problems I've run into so far was the short leg of the slide stop spring was backing out of the frame and created an outward bow in the frame, 2 of 3 magazines were not dropping free, and the sear to hammer interface wearing on only about 60% of the engagement face, and finding a recoil spring that will eject full pressure 165gr ammunition less than 10 ft.
Found the end of the short leg was jagged and catching in it's metal collar as the spring is raised and lowered when the slide stop is inserted and removed. Repeated ratcheting resulted in outward pressure toward the frame and a permanent bulge. Fixed by removing the spring and reshaping it to better fit in the insert groove and close to the frame itself (the spring already has these areas already stamped - just tweak them. Repaired the frame with low heat and clamping it back in shape The sticking magazines had an oval shaping at the upper end at the taper vs the working magazine being flat in this area - flatten the oval to fix. The leading edge of the factory sear seems to be a common problem with all P07/09 pistols regardless of Gen - CGW trues as standard practice on all their rework and upgrades - just lightly stone the leading edge where it shows a wear line as best you can. If you overdo, the trigger action will have a catch and you fix with a $20 oversized GW roller. 185gr ammunition ejections were 15 ft and I haven't found a new 40 caliber blue uncaptured recoil spring yet - tried an 18# CGW spring with same result and now using a flat wire 20# glock ISMI spring which is working OK so far.
Double/Single Action measured trigger pull weights started at 10+ and 3# respectively. The Single Action break had a soft rolling feel and was fine for practice shooting but too sensitive and easy to unintentionally trip the sear in a carry mode.
I found 1 forum user with an identical pistol who was open and provided solid input on his experiences with his polymer and metal frame CZ pistols (M1AME4).
I've done the posted polishing, CGW slide springs including their firing pin, trued the sear to hammer engagement, am using a 13# hammer spring a red .024" sear spring, a CGW trigger return spring, a .225" roller, and hammer carry back of .008" at the ring. Measured trigger pull weight are 7.25# DA and 4# SA. The 4# Single Action break is still soft and rolling but now has 2# of pretravel and 2# of creep/wall and feels good enough for carry use. You can get a sharper break feel using the CGW hammer but i'm hesitant to take this step at this point. Lastly, the trigger never really fit my finger and I've replaced it with a CGW 85 trrigger ($42) and added a solid guide rod with a 5/64" cross drilled hole to make replacing the recoil spring easier.
In retrospect, I've got the pistol working pretty well right now but had to go thru some redo's. If you choose either model expect to spend quite a bit on upgrades as you will undoubtly want to do some.
