Author Topic: New CZ 75 COMPACT with FTRB problem  (Read 2127 times)

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Offline Zak Smith

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New CZ 75 COMPACT with FTRB problem
« on: January 01, 2003, 12:31:00 PM »
I have a new CZ 75 COMPACT that is having a FTRB (failure to return to battery) problem.  

About 50% of the time, the pistol operates fine.

About 25% of the time, the slide does not return to battery, and the round's nose is stuck a little ways down the feed ramp.  If I give the rear of the slide a little push or slingshot the slide, at this point, the round chambers.

About 25% of the time, the slide "hesitates" on feeding, and it looks like it's moving in almost slow motion.

The problem first occured with factory S&B 115gr rounds.   I then put approx. 200 Speer Gold Dot 124+P rounds through the pistol to break it in, and then lubed it copiously with CLP.   The Gold Dots still exhibit the problem, and the S&B's a little less so.

Does this pistol just need more break-in, or is something more serious wrong?    My 75B-SA did need 4-500 rounds to get everything working smoothly, but it never had this FTRB problem.    My 85 COMBAT and my girlfriend's 75 COMPACT worked flawlessly from the box.

This is particularly frustrating since the Gold Dots are my self-defense load and this pistol was intended to replace my Glock 19/23/27's for CCW.

Any suggestions?

thanks
Zak

Offline ut83

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New CZ 75 COMPACT with FTRB problem
« Reply #1 on: January 01, 2003, 02:50:24 PM »
OK....sit down and get a cold one.  This could be alittle long..I had the same problem with my Compact and basically redid my entire gun before sourcing the problem.

First make sure your feedramp is in good shape...doesnt have to be mirror polished..just smooth to the touch.

Second make sure your Recoil spring is of adequate spring weight...this can be tested by locking the slide back and loading a loaded mag in the gun.  Pull the slide back until it stops..and let go..it should snap forward, strip the rnd and feed it.  Try your girlfriends Compact spring in your gun if you can...also when you shoot it..the brass should be 4-6 feet from you..it its farther away..your recoil spring is to weak..if its closer its too strong.

Once those are ruled out as possibilities...this is what eventually was found to be my guns problem.  Field strip your gun.  Look at the locking lugs on the barrel...in the front top corner of the lugs....are they chamfered from the factory?
You can tell it will have just a little 45 deg angle cut into the corner following the curve around the barrel.  If it has it..then check your slides locking lugs for the same thing.  These chamfers are designed to give clearance for smooth in and out of lock motion.  My barrel didnt have the chamfer and started to fold over or burr at the front corner of the lug and barrel hood.  My slide had the chamfers..but the barrel didnt.

If this is the case..your problem is the burrs create friction between the barrel and slide.  Take it to a smith and have it chamfered.  Or you can carefully take a jewelers file and do it your self....just touch the corner following the curve of the barrel on a 45 deg angle...dont touch the flat portion on top.

Take it down past where the "normal corner" would be..leaving a slight angle in its place....your done.

I had to touch up my barrel every 4-500 rnds but was no big deal after redoing my entire gun trying to fix it......

Let us know what you find...were here for you buddy..Shoot well

Offline Zak Smith

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New CZ 75 COMPACT with FTRB problem
« Reply #2 on: January 01, 2003, 04:15:35 PM »
The feedramp surface is about average for the CZ's I have (which work), and the spring is strong enough to strip and load the top round from slide-lock.   Ejects cases about 4-8' away, +P rounds a bit further.    

I conclude it's not a limp-wristing problem because it happens even with 124+P rounds, and my GF can shoot her pistol with my reduced velocity hand-loads (115gr @ 900 fps) without jamming and still have the slide lock back on an empty mag.

I can't really tell if the chamfer is there.   It does not appear to be so.  However, I can't see it on her "working" Compact, either.

Instead of trying to fix the pistol myself, I'm just going to call Mike@CZ-USA tomorrow.   This thing is brand new and should work reliably from the box.   It's CZ's problem.

thanks
Zak


Offline ut83

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New CZ 75 COMPACT with FTRB problem
« Reply #3 on: January 01, 2003, 04:24:37 PM »
Before you send your gun of to Mike..who by the way is a stellar smith and nice guy, check the barrel by running your finger over the top of it.  From the back of the hood ..forward.  If you feel anything that feels like it catches your finger on the corners..thats your problem.  Its SOO easy to fix...I understand your wanting to send it off..but realize Mike is a busy guy and may have your gun for a while.
Also check the locking grooves in the slide for the same type of thing that shouldnt be there....Just thought Id throw this at you....good luck and shoot well.

Offline Zak Smith

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New CZ 75 COMPACT with FTRB problem
« Reply #4 on: January 01, 2003, 04:38:42 PM »
Hmm..  I didn't find anything trying that.  If I dry-fire and keep the trigger depressed, then cycle the slide by hand, there are no "rough" spots upon returning the slide to battery.

I had Mike do my 75B-SA trigger and it's excellent.  That took about 5 weeks to the day.    My plan for this Compact is to have a set of SA-only trigger parts put in for a clean, creep-free 4.5lbs pull.  I don't mind waiting for that, and he can fix this FTRB problem at the same time.

-z

Offline ut83

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New CZ 75 COMPACT with FTRB problem
« Reply #5 on: January 02, 2003, 12:38:26 AM »
Good choice...in all honesty if it were possible Id do the same to my older PCR.  Not possible...but I could get a nickel Compact frame..convert the trigger and use the PCR topend...hmmmmmm.......
Shoot well

Offline Zak Smith

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New CZ 75 COMPACT with FTRB problem
« Reply #6 on: January 03, 2003, 12:15:37 AM »
Well, tried calling CZ today and no answer.  Maybe that was for the best...  I was fiddling with the offending COMPACT this evening, and noticed that the hang-up spot was coincident with the movement of the hammer under the firing pin block recess in the slide.

As the rear edge of the top curved surface of the hammer slides over the forward surface of the recess, it was hanging up just a little.  There is slight peening on the rear of the slide, and there was a burr on the left edge of the hammer, where it would contact that slide recess edge.

I used the "fine" rod from my Spyderco 204M knife sharpener and removed the burr on the hammer and smoothed out the surface of the hammer that contacts the bottom of the slide, giving it a little more radius.

Operating the pistol by hand seems a little smoother now.  I'll try it out this weekend and see if it helps at all.  

-z

Offline ut83

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New CZ 75 COMPACT with FTRB problem
« Reply #7 on: January 03, 2003, 07:47:17 AM »
Check out my "slide modification" in the CZSmithing section....
Shoot well

Offline Zak Smith

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New CZ 75 COMPACT with FTRB problem
« Reply #8 on: January 04, 2003, 06:12:06 PM »
Well, it turns out deburring the hammer didn't help at all.

I also discovered the inside of the frame - on the underside of the front-strap just under the magazine holding cross-bar - there's a channel of "missing" metal, as if during the mfg process it was drilled.  The recess starts about 0.15" wide and maybe half as deep, and tapers "out" to match the surface in about 1" of length.  It looks as if was "tapped" before the insides were milled or finished.    I would consider this to be a manufacturing defect.  We'll see what CZ says.

-z

Offline kahrpacker

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New CZ 75 COMPACT with FTRB problem
« Reply #9 on: February 06, 2003, 01:08:16 PM »
1) Hone feeding ramp to mirror finish. Go all the way from the bottom of the ramp to inside the chamber. I use a Dremel, felt-cone and automobile rubbing compound. You can clean the barrel with soap and water, dry it thoroughly and oil it.
2) Use Wolff's spring kit to increase recoil spring by 2# at a time 'til problem goes away.
3) THEN, if the problem continues, seek professional help.
:lol
Bren

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New CZ 75 COMPACT with FTRB problem
« Reply #10 on: February 06, 2003, 01:23:07 PM »
kahrpacker,

Thanks for the suggestions.  

I knew I could polish the feed ramp to help the problem.  I am skeptical of increasing spring weight because doing so will generally decrease reliability (e.g. failures to eject, lock back slide; more susceptible to limp-wristing).

However, there's no way I'm going to succumb to being required to hack on a brand new pistol to get it to operate properly.  On principle, a brand-new pistol should work 100% from the box.  Mine didn't and I sent it back to CZ-USA for them to fix it.

regards
Zak

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New CZ 75 COMPACT with FTRB problem
« Reply #11 on: February 07, 2003, 01:22:16 PM »
Changing the springs makes it unreliable?  Which one, mag?  Recoil?  To what weight?  I call BS.  I run 18-22# recoil springs in all of my Compacts, PCR's and PO1.  Ive had no failures of anykind regarding any ammo, even WWB.  Find the spring weight that shoots target ammo reliabley and keep going up in spring weight until you get a failure and go back down in weight one step.  
Anything youve heard about decreased reliability because of Wolff recoil/mag springs is complete BS.  Ive ran them for years in every gun Ive had.  
Polishing the feedramp correctly requires: a dremell tool w/ polishing tips  and jewelers rouge and 10 seconds.
Car compound will take you a zillion years but hey its your time.  You can scotchbrite it a little if needed and then polish it with the dremel if you have scratches to get rid of.  Start with small steps and stay with them.
It doesnt need to be a mirror to load empty cases...which my guns will do.

Offline Zak Smith

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New CZ 75 COMPACT with FTRB problem
« Reply #12 on: February 07, 2003, 08:41:59 PM »
CZELITE,

I am talking about the recoil spring.   I have no beef with Wolff springs, as you said.

It's a fact that autopistols that operate generally like a CZ, Glock, 1911, etc, depend on both slide velocity relative to the frame, and "enough" slide motion relative to the frame.  If it's going too slow, it may fail to eject or clear the port.  If it doesn't reach its rearward limit, it may fail to eject, fail to strip the next round, fail to chamber it properly, or fail to lock the slide back on the last round.  

To see these failures occur, just keep increasing the recoil spring strength.  Alternatively, shoot extra-low power rounds in your factory-sprung CZ to see the same effects.   You should start to see such failures with a 115gr around 850-900fps in a CZ.  115gr@900 will not operate a Glock.  I have not done experiments to see how much one must increase spring strength to induce the same failures using factory ammo.

For a pistol in a defensive role, I want the most margin between each firing event's conditions and the various failure conditions.    In the case of the recoil spring, there will be an upper and lower limit to this "reliable" range.  Spring it too low, and the gun will probably unlock too soon, putting extra stress on the case itself (not to mention frame battering).  Spring it too high, and the gun will hit those failure modes listed above.  In a defensive situation, I want to avoid both problems, taking into account factors that can change the conditions that effect operation of the pistol.

Examples of these might be: limp-wristing for whatever reason, maybe I'm in a 1-handed retention hold; maybe the cartridge fired is on the extreme low spread of the deviation; maybe the slide is extra gunked up; maybe my thumb rubs against the slide, etc, etc.     Some of these may never be a problem in normal training and practice, but may be if me and my equipment are pushed.

If I follow your advice and pick the next spring below the one that produces failures, then there is less margin between the average conditions and the failure conditions, than if I stayed with the weaker stock-weight spring.

BTW, I do agree that increasing the spring weight may alleviate my feeding problems, since the cartridge will have more force pushing it up the ramp.

regards
Zak