Slide won't lock back, round won't strip from mag

[gunner01]

I have a CZ 75 Shadowline compact that I just did some work on, I did not fire a lot of rounds through it before I decided to do the work but the couple of hundred I did fire the gun worked as it should.  So, I must have screwed something up with my work.  All CZC parts, comp hammer, 13lb hammer spring, ext firing pin, rami fp spring, pre b disco, and 11 lb recoil spring.  I did some polishing while I was in there.  Got it all back together and the empty gun appears to function properly with regards to trigger and resets and such and the DA/SA trigger weights are reduced significantly.  The problem is the slide will not lock back.  Will not lock back manually or with empty mag in the gun.  Also, rounds will not strip out of the mag when loaded mag is inserted into the gun and the slide is racked.  Every so often a round will feed partially from the mag but the round jams badly while trying to go into the chamber.

 

I did some pretty aggressive sanding/polishing to the trigger bar (especially the sides that contact the frame).  I also noticed that the humps on the top of the trigger bar that the slide rides on, (especially one side) seemed misshapen and uneven so I rounded them over and polished them thinking the slide would ride back much smoother.  Do you guys think I may have screwed up and taken too much off the trigger bar humps to cause the malfunctions that I am seeing?  If not any other suggestions.  TIA

Edited January 11, 2019 by gunner01

[regor]

1) Does this happen with all magazines? My first instinct for not locking back and feeding properly is a mag problem, not a gun problem. Are the mags original (i.e. no custom followers like Grams or CZ Custom, or basepads that might not be designed for the 14 rounders for the compact line)? Take the slide off and insert each magazine empty. Do the followers push up on the slide release? If not then something is wrong with the (a) the follower, (b) the magazine not getting inserted enough. Since you are having feeding issues (b) seems more likely. If you press down the mag release, can you push the magazine up further? If so, you probably have an issue with the mag release. Maybe it's worn down and locking in the magazines just a little too low. If not, and you have an aftermarket base plate on, swap it to the original factory one and see if the issue persists. 

 

2) Can you manually push the slide release up and get it to lock? There is a little notch in the slide on the left side where the nub from the slide stop is supposed to lock in. If you sanded that area or the nub too aggressively the slide release nub might be slipping out of the notch. This would explain no lock back but not feeding issues. 

 

I don't think the trigger bar would cause this. Messing up those bumps might mess up things with the trigger but I don't think the bar interacts with the magazine/slide stop.

 

[gunner01]

Thanks for your response.  This is a brand new gun with new factory standard mags ( approx 200 rds fired before my modifications).  Slide will not manually lock back (mag or no mag).

 

I did not polished rails on slide or frame and I did not polish the slide stop.  I did polish the frame a little on both sides where the trigger bar contacts it.

[regor]

Then I would guess it is an issue with the slide stop or the slide itself, though as before this really does not explain why you are having feeding issues. Do you have another CZ you could swap the slide/slide stop with? 

[gunner01]

Well I found the problem.  I removed the 11 lb recoil spring that CZC sold me (standard round wire type part #30016) and put the factory original flat wire type recoil spring back in it and it is dry functioning as it should.  I asked CZC to sell me the exact parts that they use when they customize one of these Shadowline compacts.  The 11lb CZC spring was a lot longer than the original and it "bunched" up around the recoil spring guide.  I assume this compressed and held the slide just short of a complete stoke during racking.  I would think that this gun would need a shorter spring like the original so I will call CZC and confirm that they sent me the right spring for this compact.

 

 

Edit 1. Just took it outside and it is running like a top.  

 

Edit 2.  Talked to CZC and they confirmed that that spring is for a full size and will not work in a Compact.  They also said that they do not change recoil springs in the Shadowline Compacts that they customize.  So just some miscommunication on the prior order.

Edited January 11, 2019 by gunner01

[regor]

Ahhhh that makes sense, I never would have thought about that. If you want a lighter spring you could try to just snip a couple coils off the original one.