Need Help with Odd CZ Problem

[Tecolote]

I ran into an odd problem with my CZ75B at the range. Two times while using Winchester SaverPack FMJ ammo, the slide locked back on a loaded mag, first time one mag had 3 rounds left and the other time a different mag had 4 rounds left, the problem happened with consecutive loaded mags. Each time the slide locked back, the top round was pushed slightly forward, but they didn't hit the ramp. The mags came out normally, I didn't have to use any force to remove them. After I removed the mags, I pushed the round backs into the correct position, inserted the mags, closed the slide using the slide lock, and fired the rounds in each mag without any problems.

Before those two times my CZ has worked 100% and the rest of the ammo worked perfectly, even Blazer that's caused headaches for other CZ owners.

Since it happened only once with each mag, I think that the problem might have been caused by my grip, maybe I accidentally activated the slide lock, or maybe it was an ammo problem, but I'm not sure how.

What could've caused the problem?

 

[Rumble]

You may have inadvertently activated the slide lock; if your grip puts your finger near it, it's certainly possible.

I had a similar problem with my P-01, where the slide would lock back before the magazine was empty. The recommendation I got was to replace the magazine springs with Wolff increased-power mag springs, because the springs might just not feed the round quite fast enough. That solved the problem immediately. In fact, I have one mag that hasn't had the spring replaced (I had 4 mags, and the springs come in sets of three), and it locks back on that one still.

On the other hand, if you've already upgraded the springs, then it's something else!

 

[railroader]

If it continues to do this you can add a little tension to the slide stop spring. Take the spring out and bend the knee portion slightly then put it back in. I have a charles daily dda which is a cz clone that had the same problem alot. Bending the spring fixed it. Mark

 

[Destructo6]

I had a similar problem while using aftermarket mags that were made for Tanfoglio pistols. I have not had this problem with factory CZ mags, though.

 

[GaryArkansas]

Hmmm, since it happened to two different mags (I presume), the problem is not likely the mags. I'm wondering if its a spring issue?

What does your ejection pattern look like? What's the condition of the recoil spring?

 

[Tecolote]

The brass gets ejected forcefully, unless I my loosen grip, but that's typical of any auto I've handled. The recoil spring looks fine. FWIW the mags are MecGar OEM and not the Czech made CZ mags. The problem only happened twice, but I wouldn't mind replacing mag springs or even the recoil spring to insure 100% reliability.

 

[briang2ad]

Could still be the mag springs - both are waek - can happen in a CZ

OR: Could be that rounds are tapping on the slide stop - the slide stop COULD be 'out of spec' and have a little too much metal and be hitting the rounds feeding in. You can see this by taking the SLIDE OFF the gun, inserting the slide release, and popping in a mag with ammo or snap caps of the same OAL as your ammo. Note the slide is OFF. Then you can see if this is the case - the stop touching the rounds. My 40 did this, because CZ had put in a 9mm slide stop - not good. 9mms can do it also.

Or - your opposing thumb may be hitting the stop with a high hand hold.

 

[Steve C]

Could be the springs and it could be the shooter accidentally bumping the side stop with his thumb during recoil..

 

[goon]

I think its a bullet profile or OAL cartridge length thing. I have had this before and I solved it by looking at how things connnected (the bullets were brushing against the inside of the slide lock and pushing it up) and then carefully fitting the slide lock until it allowed the bullets to pass without touching.
If you try this work slowly or you will deactivate your slide lock altogether.
And I did this on a Kahr P9, not a CZ.