My history with CZs has been full of frustration and disappointment. I was having a pretty good run with my second .40 S&W CZ-75B, but now it's returned to "jam-o-matic paperweight" status, and I'm pondering my options.
A little background:
My first CZ, a CZ-75B in .40 S&W I purchased in 2003, was garbage. It wouldn't feed or extract reliably with anything but Sellier & Bellot FMJ, and I don't have room in my life for a gun that will only work with one brand of ammo. After a couple of factory repair attempts, replacing the extractor spring, and replacing the recoil spring, it still wasn't reliable. The last straw was when half of the safety lever flew off during firing. CZ had me send in the remains and replaced the gun under warranty.
The replacement .40 S&W CZ soon proved almost as unreliable, whether I used factory ammo (Winchester white box, mostly) or my reloads. The same malfunctions happened, just a little less frequently.
Swapping out the stock springs for a Wolff standard-power recoil spring and extra-power extractor spring magically made things OK for the next 5000 or so rounds.
Then, a few weeks ago, extraction failures started happening again. It occurred with the same reloads (3.5 grains Titegroup under a 180 grain, moly-coated cast lead bullet) which had worked fine for 500-600 rounds. Usually, if I have doubts about a gun, I test it by running at least 100 factory rounds through it. However, I am reluctant to throw good money into a known-unreliable gun, especially with the ever-increasing price of factory ammo (30/round and up locally for .40 S&W).
I promptly replaced the recoil spring, extractor spring, and even the firing pin spring. No dice. The gun still has "double feeds" every couple of dozen shots or so. The extractor just isn't doing its job.
The brass I'm reloading is not especially worn out. While I have reloaded most of it several times, it has almost all been mild loads, some up to 20% below max pressure. What I'm saying is, I don't think my reloads are the problem, and it isn't my shooting technique either. My other autoloaders, including a 1911, Glock 30, S&W M&P, and Ruger Mk II, have had no such problems.
The gun certainly shouldn't be worn out. The extractor itself looks fine, with no unusual wear, chips, or cracks.
I don't understand why a gun would be reliable for several thousand rounds in a row, then start to suck again.
This isn't the first or even the second time I've had trouble with a CZ. I briefly owned a CZ-2075 RAMI in 9mm that went through a similar "multiple malfunctions, replace parts, send gun in for repair, gun still malfunctions" cycle. Once was enough, there; I traded it in on a rifle. My girlfriend had even less patience with her compact .40 S&W CZ-75B. CZ attempted to cure its feed ills by polishing the feed ramp, but when that also failed, she sold it quickly.
I've thought about sending my CZ in for warranty service yet again, but I'm not sure I want to deal with the hassle. While CZ will pay the shipping for warranty work, they insist on having FedEx pick it up, which is inconvenient and problematic in its own ways. I am also hesitant to waste reloads on testing it still another time when it gets back. My .40 S&W M&P has been 100% reliable from the start, and this with a steady diet of my reloads. I am very close to just selling my last CZ & moving on. What would you do?