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Locked up tighter than...


rhart123

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My P-01 slide has locked up while chambering a round three times now. It does not go all the way into battery when it happens and I have to use a rubber mallet to break it loose. Happened twice with Tula and once with WWB (both 115 grain FMJ round nose ammo). After I got the slide loose I took the round and dropped it into the chamber with no problems. Anybody have any thoughts on this?

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Agreed. CZ's have short chambers. I load to 1.075" using Flat Point bullet profiles. Round nose profiles should be able to go a bit longer, around 1.15-1.2" which is pretty near SAAMI spec if I recall. Remove the barrel and do the plunk-and-spin test with those rounds. Make sure they spin easily, dropping it in alone isn't a good test.

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Check the extractor groove of the brass in question. I have had that happen before, round chamber checks, spins, drops out, but locks up the gun. Turns out that the extractor groove was too big. The extractor was getting wedged into the groove too tight, and the force of the slide going forward would wedge the case into the chamber. It was a very specific brass, and once I weeded all that brass out, it never happened again.

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Seems to make sense. I mean after you took a mallet to the gun, you most likely reduced the overall length of the cartridge. It stands to reason that the new and shorter overall length chambers just fine.

FWIW, my CZ likes 1.085 overall length but that's with reloads using 124 gr MG JHP.

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I did try to force it into lock up the first time it happened, but I thought that made it lock up even tighter. The next times I didn't beat the slide forward, I beat it backwards only to unlock it. But in any case I didn't measure the OAL since I didn't have a caliper with me. I put the bullet back in the gun and it shot just fine. The next time I will save the bullet and measure it. I was thinking it was probably the gun since it happened on two different brands of factory ammo. I never had this happen on any of my other CZs - SP01, P-07, 85C, 75 Compact .40.

Edited by rhart123
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Sounds to me like a Plunk Test might help.

(Before you try to load the rounds into the chamber). :cheers:

I agree. I would also see if the round can be spun in the chamber as well.

I ream my barrels because I typically load to the max length my mags can take but most CZ owners won't go that route.

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  • 1 month later...

Finally got a caliper out and took some OAL measurements of three different brands of ammo - WWB 115gr ran 1.149 to 1.154, Federal 115gr ran 1.147 to 1.151 and Freedom Munitions 147gr. ran 1.147 to 1.156. Seems kind of long for all three compared to what you all are loading to. I also measured my carry ammo (Remington Golden Saber 147gr HP) and got 1.105. I had no issues with my carry ammo during testing. Plunk test revealed that Federal would spin fairly freely while WWB would spin with force and I could not get Freedom munitions to spin with as much force as my arthritic hands could muster. All the rounds that would spin showed some rubbing on the projectile - even a little on the Golden Sabers...

The caliper was borrowed and I did not like it as the faces of the jaws weren't even all the way across, but had a "beak-like" appearance and all the measurements had to be within the short distance at the end where the flats of the "beak" were. So I'm not real confident of the measurements made.

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If they are hitting the lands before the slide completely closes then that is the problem. I had some loaded too long for my Tanfoglio Limited 9mm and had the same problem. It was locked up so tight I couldn't rack the slide at all by hand. Buy round nose projectiles if you are loading long, the bullet profile will allow the cartridge to chamber properly.

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I wouldn't expect Freedom 147gr @ 1.15in to spin at all. I have to load much shorter to get 147gr to spin freely in my CZ which is why I don't load 147gr at this time. Rubbing on 115gr rounds leads me to believe your CZ has an unusually short chamber but don't rule out the extractor ALSO contributing to your woes.

Time to find out your Max OAL. http://www.czfirearms.us/index.php?topic=34225.0 I'd invest in a good set of calipers.

Vince

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The gun locks up with the bullet about halfway in the chamber - way before the lands are engaged. About 1/3 to half the brass is visible when this happens.

You should drop those rounds into a chamber checker. Either the brass is crooked or the shoulder of the bullet is hitting the lands.

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