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jumpingjackflatch

jumpingjackflatch

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I have a CZ 75 SP01 Shadow. I have only put about 400 rounds through it. I have noticed the slide only locks open on the last round about half the time.
I am using stock magazines and S&B 124gr factory ammo. Is there something I should inspect on the mags or gun that may reveal why this is happening? I have
googled it but most things relate to worn mag lips or reloaded ammo. any ideas?
 
jumpingjackflatch said:
Yes. There is a big chance that is the problem. It never occurred to me. I will check it out next time I am at the range.
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I tried putting 1 round in the mag and fired it one handed. Out of the six times I tried it, it only locked open twice. I Used two different magazines. The gun was clean. I was hoping it was my thumb on the
slide release, or the magazine had a problem, but now it doesn't look like it.
 
Put an empty mag in the gun and rack the slide, look inside and see if the tab is lifting the slide release, if not you may need to bend it a bit til it works.
 
Skinny 1950 said:
Put an empty mag in the gun and rack the slide, look inside and see if the tab is lifting the slide release, if not you may need to bend it a bit til it works.
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When I put an empty mag in and rack the slide, it always locks open. Someone at the range said that maybe the recoil spring is a bit heavy and it will loosen up with use.
 
Get enough crude in the mag and the follower will sometimes stop coming up high enough to engage the slide lock.
Probably not your issue if it's still new enough to be breaking in but a consideration.
 
have you taken the mags apart? Most common mag issue is the spring being in wrong. See if you can identify specific mags that are the problem.
 
By the sounds of all this it seems like your recoil spring is a bit too stiff. I'd get a new stock recoil spring. Springs can vary from their nominal rating by some amount and it's quite possible that your spring is on the hard side of the tolerance value range.

It may or may not soften up with use. But we're talking about quite a few thousand rounds to find out. Much better for the gun and your own enjoyment to put a new recoil spring in it.

It seems hard to nail down the stock spring rates for the different models of CZ. But I gather that for the Shadow you want a 15lb spring. While I was at it I might pick up a 13 lb to try at the same time.

Another thing you can try while waiting for your spring order to arrive is to clip off a single turn from the front end of the spring you have now. That will reduce the amount of preload. If that fixes things then you are good. If you still get some failures to lock back then try ONE more turn. If that doesn't do it then don't go further. Shortening the spring beyond a small amount has the effect of increasing the stiffness. By clipping it at all you're playing with the balance between the amount of preloading and the final stiffness. Go too far and it'll mess up the timing of the delayed blowback operation.
 
BCRider said:
By the sounds of all this it seems like your recoil spring is a bit too stiff. I'd get a new stock recoil spring. Springs can vary from their nominal rating by some amount and it's quite possible that your spring is on the hard side of the tolerance value range.

It may or may not soften up with use. But we're talking about quite a few thousand rounds to find out. Much better for the gun and your own enjoyment to put a new recoil spring in it.

It seems hard to nail down the stock spring rates for the different models of CZ. But I gather that for the Shadow you want a 15lb spring. While I was at it I might pick up a 13 lb to try at the same time.

Another thing you can try while waiting for your spring order to arrive is to clip off a single turn from the front end of the spring you have now. That will reduce the amount of preload. If that fixes things then you are good. If you still get some failures to lock back then try ONE more turn. If that doesn't do it then don't go further. Shortening the spring beyond a small amount has the effect of increasing the stiffness. By clipping it at all you're playing with the balance between the amount of preloading and the final stiffness. Go too far and it'll mess up the timing of the delayed blowback operation.
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I'll drop by Tenda tonight and pick up a factory recoil spring and a 13 lb spring and try them out. A stiff factory spring seems like the most logical culprit.
 
get someone to videotape you shooting, one handed and with two hands, showing this happening and post that here. I have yet to see a Shadow not lock back because of recoil spring problem, and I only see a few thousand of those guns a year at matches and my classes. Many people, and yes in IPSC, run the factory recoil spring in their Shadows and have zero issues. Changing recoil springs is all about tuning your gun so the sights return to target properly, that's it. I have seen Shadows with mechanical defaults in them that prevent the slide from moving properly and not locking back or cycling correctly, but never a too stiff recoil spring. Plenty of mag issues, and the single number one issue is the shooter himself.
 
Okay, I mentioned this problem to a guy that is into these guns. He took off the slide and then removed the extractor. He cleaned it with G96, then cleaned the spring and channel. I took it to the range tonight and it locked open every time after last round.
I do clean my gun but haven't removed the extractor yet. I don't see how this would cause the problem, but it seems to be fine now.
 
The .40 mags when used with 9mm ammo will lock open on the last round because the 9 has a smaller diamiter than the .40 allowing the follower to engage the slide lock even though a cartridge remains, my xd9 does the same thing
 
the extractor would have nothing to do with the slide not locking back unless it wasn't releasing cases when the slide went backward, that would be tough to happen. when an extractor gets dirty and gummed up it normally gets slowly pushed away from the breechface until eventually it won't hold onto cases during extraction, causing other issues. But that takes thousands and thousands of rounds to happen.
 
jumpingjackflatch said:
Okay, I mentioned this problem to a guy that is into these guns. He took off the slide and then removed the extractor. He cleaned it with G96, then cleaned the spring and channel. I took it to the range tonight and it locked open every time after last round.
I do clean my gun but haven't removed the extractor yet. I don't see how this would cause the problem, but it seems to be fine now.
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Think you might have answered your own question. New pistols of good quality, which CZ's are, start life with a tight fit. Usually a through cleaning and lubing will do wonders until they break in. Tolerance's are really tight right now it doesn't take allot of crud to hang up things.
 
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