A CZ75B problem is driving me crazy!

A

AndyP

New member
OK, I've been to two IDPA shooting classes these last two Sundays. Both days I had the following problem:

The gun functions flawlessly for the first 250 rounds or so, but after this I start to have malfunctions, namely, occassionally a spent case remains in the gun and becomes jammed in horizontally. (To clear it I have to drop the mag, cycle the slide, and sometimes tip out the cartridge.)

As I said, this has happeneed two shooting sessions in a row, so I don't think it's a fluke. The ammo (reloads) remained the same thoughout each session and the problem only showed up after 250 rounds.

Does anyone out there have an idea of what this could be? If the extractor spring were weak, wouldn't it show up right from the beginning? Ditto with the ammo? Could it have anything to do with the gun getting dirty or hot? I'm stumpted!

Any ideas?
 
Hello. What load are you using? IF it's barely enough to make the gun function, as the gun gets dirty, the slide velocity rearward may not be enough to eject the round.
Thus, the slide could come forward, trapping the case, and causing problems. It is hard to diagnose from a distance.

I think an extractor problem would show up without the gun being dirty, but IF it was right on the edge, it could show up later.....I guess.

Best.
 
Andy,

You mentioned that this problem only occured after the 250 round mark, on two consecutive occasions. You are correct when you said that if it were a mechanical problem, that it would have shown up from the beginning.

What you mostly have is an ammo problem. Some powders typically burn "dirty". They work great, give great accuracy, but after a certain period of time the accumulated residue can make your weapon start to jam and malfunction.This is especially so when using lead bullets instead of jacketed. Lower overall pressures leading to less efficient powder burn, bullet lube residue, and lead shavings may accumulate causing this problem. In addition, when a bullet is fed from the magazine and into the chamber, the bullet nose sometimes makes contact with the upper part of the chamber, leaving another place for residue to be deposited.

If you reload your own, try a different powder, if you purchase reloads, purchase them from elsewhere and see if you notice a change. I think you will.

Good Shooting
Red
 
I've had a nearly identical problem with my CZ-75. The description of the stoppage sounds absolutely the same. The story was the same regardless of the ammo used (Fiocchi, PMC, Speer Lawman, Blazer, etc).

While installing a new extractor spring I realized the old one was only about 2/3 the length it should be. There was also an incredible amount of burnt powder residue in the extractor slot (about like an AR).
 
I had the same problem with my cz and reloads, found
the chamber a little tighter then other 9mm's so I
purchased a lee factory crimp/sizer die and problem
went away.
 
Thanks to all of you who have replied so far. This is why TFL is so great.

In a perverse way I'm glad others have observed the same thing. I was using my own reloads, but with a very clean powder, Vihtavouri 3N37. Of course, the primers (Winchester WSP) aren't clean. In the first session I was using rounds at the VV manual's minimum for 124 gr. bullets in 9mm, namely 6.1 grains. For the second I increased the charge to 6.3 gr. I would think if it were ONLY underpowered ammo the problem would be intermittent. However, maybe it is a combination of "borderline" powered ammo AND the gun getting dirty, as Stephen and Redlg155 suggest. I'm starting to think that CZs like their ammo hot.

The price of a tight slide fit and excellent accuracy is more susceptability to dirt, I suppose.

Destructo6 and bullet44's comments are also relevant. Destructo6, is it possible to remove and clean the extractor channel without too great a gunsmithing skills? I will have to check the remaining ammo in my Dillon 9mm chamber gauge. I've been loading to an OAL of 1.145". I current use the Redding Pro Series taper crimp die, but maybe I should look into the Lee resizer, too.

Again thanks, and I hope more people will respond if they have had this kind of problem and say what they think about it. I will now have to try some S&B or hot NATO ammo and see if (after a whole lot of shooting) the problem shows up.

AndyP

[Edited by AndyP on 03-26-2001 at 01:15 PM]
 
The extractor is pretty easy to remove. Place the bare slide, right side up, on a bit of wood with the front quarter of the slide hanging off (the part that's not flat). Take a small punch and drive the extractor pivot pin straight down. There's no need to drive the pin completely out of the slide.

Use something non-marring, like a brass rod or hammer, to drive the pin back into place. It only needs to be flush with the bottom of the slide.
 
The tight chamber comment above makes a lot of sense -- for by that numbder of rounds, the barrel is probably getting hot, and while it will expand, some of the expansion may be inward, too.

(As I noted on the CZ forum, I had a similar problem with my CZ-85 Combat, but that had to do with the slide stop and how it was interacting with magazines. My gunsmith looked at it for a while, played with it, and took a little metal off the stop -- and its been flawless ever since.)
 
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