Failure to Feed

[Rodolfo Fierro]

I bought thisused 75BD and love shooting it.  Sometimes a cartridge does not chamber completely.  When the jam occurs the bullet is touching the top of the chamber and the cartridge is completly out of the magazine.  So there is an upward angle of the cartridge and it is less than half in the chamber.  Magazines were tested on another gun and they worked fine.  Any ideas ?

[GhostWarrior]

         Since it's used, check to see if the serial number on the barrel matches the serial number on the receiver and slide. It sounds like there is an issue with the ramp, and one reason for that could be someone swapped out the barrels for whatever reason and it wasn't fitted properly, and it gets out of sync now and again. or it needs to be polished.

         I'm pretty sure there's also another cause it could be but I can't remember what it entails exactly. Someone here will most likely have an answer that explains the real reason. If all else fails call CZ-USA and ask their gunsmiths for an opinion.

[TexinMaine]

Sounds like you could also have a fouled up feed ramp. If the feed ramp is dirty it will cause problem chambering a round. Hopefully the fix will be as easy as a good cleaning. Make sure your chamber is cleaned good as well.

Tex

[Rodolfo Fierro]

Thanks for the polishing tip.  I have the prettiest feed ramp that you have ever seen now.
After cleaning the gun and lubricating it I was able to duplicate the failure with a snap cap.  I want to change the description of the failure now.     FAILURE TO GO INTO BATTERY !
The cartridge is less than half into the chamber when the barrel moves to the rear to go into battery.  It is really the barrel not comming back as much as the cartridge going forward. 
I called CZ USA, the gunsmith there said that most likely a weak recoil spring that would cause this.  He transfered me to the parts dept. and I ordered a new spring and guide rod.   

[GhostWarrior]

oh ok that sounds great. Please keep us up todate on how things turn out after the swap out?

[Rodolfo Fierro]

The 18 lb recoil spring cleared most of the problem.  One magazine never fails now.  Once in a while the problem crops up with certain magazines.  I need more range time to determine which ones.  These magazines work fine if I use them in my 75c.
I ordered a 16 lb spring from Brownells.  The 18 lb seems too strong.  What weight springs do you guys use for factory ammo?

[Rodolfo Fierro]

The Wolff springs that I ordered from Brownells arrived.  The 14 lb spring is labeled "Standard Full size models" and comes with a firing pin spring and a main spring.  The 16 lb is labeled "Extra Power" and comes with a main spring.  They were only $6 each with $6 shipping. 
In the mean time I have put a bevel on the rear of the Firing Pin Block Lever and polished it.  It could have been the problem, hanging up on the Firing Pin Block.  Testing has to wait for the weekend. 

[Rodolfo Fierro]

Polishing the firing pin block did not help resolve the problem.  Grinding the "corner" off of the extractor fixed it.  Yesterday I shot the gun without failure with the 14 lb spring in it.  I tested ten magazines and all worked fine.  Simply making the inside lower corner of the extractor less square did the trick.  With all of the polishing that I did, it is now necessary to wear sunglasses when you field strip the gun. 
Shiny

[Angryvikingman]

Awesome. Glad you got it ironed out. I need to get together with GM and a couple other guys and make some basic reliability and function improvement videos for the forum. I only have the one CZ, but maybe I can find some collaborators for the project.

[GhostWarrior]

        Possibly we can make some test videos when we get together next year. I will have a few CZ's we can use for the project, Presuming Dan brings his fancy camera I have a fold up cloth light box we can use to take the pictures in, on with. I think GM lives fairly close to Dan so maybe they can get together sometime. Not real sure on locations, and distance's