CZ ammo issue

[wv109323]

 Today while practicing I had two failures that the slide did not go into full battery. The slide could not be cycled by hand. I had to hit the front bottom of the slide against a board to get get the slide to cycle and get the round out of the chamber.  One time the hammer fell but did not impact the primer. The second time the hammer would not fall. The second time the slide was about 1/8- 3/16 OOB.
 I brought the two rounds home and they easily fit in and out of a case gauge, There are no marks on the bullet or case where it was contacting anything.
 The rounds are my reloads. They are a PC 120 TC bullet sized to .3570 and and an OAL of 1,075. Both times it was on the last round in the magazine. I shot a little over 100 rounds and this happened about midway through the practice session.
 All rounds were passed through the case gage prior to going to the range.
Any thoughts on the cause?

[Grendel]

100% your reloads. Did you check your OAL in the barrel? I'm moving this to the ammunition forum, where you should peruse the stickies for the answer to your common problem in CZs.

[Earl Keese]

You will quickly be told here that a case gauge isn't the same as the chamber in a particular barrel. That said, which chamber gauge are you using? I use a Hundo and find that it works well for my CZ's. I load .357 dia as well and find that case wall thickness varies between manufacturers which occasionally causes problems.

[SI VIS PACEM PARRABELLUM]

^^^Yep this. Follow the stickies and plunk test info for setting up your OAL to fit the CZ chamber. Definitely your reloads are too long.

[Wobbly]

Today while practicing I had two failures that the slide did not go into full battery. The slide could not be cycled by hand. I had to hit the front bottom of the slide against a board to get get the slide to cycle and get the round out of the chamber.  One time the hammer fell but did not impact the primer. The second time the hammer would not fall. The second time the slide was about 1/8- 3/16" OOB.

> Classic case of improperly sized (dia or length) ammo. Can be caused by the case, taper crimp, bullet, or OAL.

> As per the template in the Stickies, we'll need to know more about your pistol, your reloading setup, your dies, and your bullet.

> Please tell us the steps you took to developed your OAL for this cartridge.

I brought the two rounds home and they easily fit in and out of a case gauge, There are no marks on the bullet or case where it was contacting anything. All rounds were passed through the case gage prior to going to the range. 

> The case gauge is supposed to be a mirror of the barrel's chamber, but many do not. You can't blindly use a case gauge to tell you anything until you do comparisons between the gauge and your chamber. If your case gauge is one of the multi-chamber devices, then you really have your work cutout for you because each individual chamber has to be verified.

> Since the case gauge can't be believed at this point, what were the measured dimensions of the finished cartridge ? Please give us ALL of the dimensions.

The rounds are my reloads. They are a PC 120 TC bullet sized to .3570 and and an OAL of 1,075. Both times it was on the last round in the magazine. I shot a little over 100 rounds and this happened about midway through the practice session.

> What is a "PC 120 bullet". We'll need photos and links.

> Just to satisfy my curiosity, have you been following the CZ reloading guidelines in the Stickies ?

 

[toteone]

Both times last round in mag?  Seems suspicious.  Possible spring issue.  Not ruling out anything mentioned, just an idea.

[bonj]

CZ warranty reply for my CZ 75B Omega:
Based on the wording it appears correct, they could not find any issues normally with the firearm. They confirmed the function but also lengthened the chamber throat to allow the fitting of larger than standard ogive ammunition as mentioned in the latter part of the Gunsmith’s notes.

As the request was written and added to the RMA, your words were: “The firing pin tip is not visible in the slide if you push on the firing pin at the rear of the slide.” The Gunsmith confirmed the firing pin was normal with no damage and added that information to the case notes so that there were no misunderstandings.
                                                                                                                                                                                                                                       
However, based on no issues being found with the firing pin the only other possible issue that would prevent the firing pin from contacting the primer would be due to the slide not being fully closed. When this occurs it is usually from larger than standard ogive ammunition, or cases being slightly too long for this C.I.P.(European standard) dimensioned chamber.


The chamber throat is an area of clearance for the projectile to sit, so that it does not contact the rifling when the cartridge is inserted into the chamber, as seen in this drawing of a rifle chamber from the internet: 

[No photo supplied, as was suggested in the text]

Instead of using a CIP reamer we use a SAAMI reamer. As for your 2nd question, it is unlikely that a stainless guide rod would resolve any issues of that nature, they would more likely instead cause issues with feeding from the increased friction.

[SI VIS PACEM PARRABELLUM]

CZ warranty reply for my CZ 75B Omega:
Based on the wording it appears correct, they could not find any issues normally with the firearm. They confirmed the function but also lengthened the chamber throat to allow the fitting of larger than standard ogive ammunition as mentioned in the latter part of the Gunsmith’s notes.

As the request was written and added to the RMA, your words were: “The firing pin tip is not visible in the slide if you push on the firing pin at the rear of the slide.” The Gunsmith confirmed the firing pin was normal with no damage and added that information to the case notes so that there were no misunderstandings.
                                                                                                                                                                                                                                       
However, based on no issues being found with the firing pin the only other possible issue that would prevent the firing pin from contacting the primer would be due to the slide not being fully closed. When this occurs it is usually from larger than standard ogive ammunition, or cases being slightly too long for this C.I.P.(European standard) dimensioned chamber.

This is a common mistake those who don't fully understand the operation of the machine make. Simply pushing the firing pin from the rear will not allow it to move into the chamber unless the firing pin block is depressed as well to release it. Hence the reason the gunsmith found no issue with it.

CZ warranty reply for my CZ 75B Omega:
As for your 2nd question, it is unlikely that a stainless guide rod would resolve any issues of that nature, they would more likely instead cause issues with feeding from the increased friction.

Not sure who came up with this but it is incorrect information. The steel guide rod will not increase friction in any way. They are a common upgrade and CZ even has sold them in the past. Never had any issue of any kind with a steel guide rod in any of my CZ's or any other gun that I added them to for that matter.

[M1A4ME]

It's just a CZ75 issue.

Ammo (124 grain hollow point reloads that I used my P01 to plunk test (cause everyone knows CZs have shorter chambers) would not reliably chamber in my M&P 9MM with an Apex barrel in it.  Yeah, guess the Apex barrel has an even shorter "chamber" than my P01.

My son's Beretta 90-Two .40 S&W has a shorter chamber than my P07 .40.

My XD .45 has a shorter chamber than my M&P .45.

So, it comes down to using the barrel you intend to shoot the ammo in for the plunk test - or find the barrel of the pistol with the shortest chamber you own and using it to check/plunk test for max COL for the ammo you load in that caliber.

And, yeah, if a CZ can't go fully forward on the slide the hammer hits the bottom rear corner of the slide and that stops it from hitting the firing pin.  At least it does on mine.

[Wobbly]

However, based on no issues being found with the firing pin the only other possible issue that would prevent the firing pin from contacting the primer would be due to the slide not being fully closed.

This is a true statement, IF as noted by SVPP, the pistol's firing pin block mechanism is working correctly.

When this occurs it is usually from larger than standard ogive ammunition, or cases being slightly too long for this C.I.P.(European standard) dimensioned chamber.

This is not an entirely correct statement. Yes, incorrectly shaped ammo can keep the slide from "going into battery", which will then implement safety measures built into the mechanism of the pistol. But there are several reasons pertaining to the ammo which can cause this. I know of at least 3...

1. Bullet colliding with the rifling. IOW, OAL is too long for that specific bullet-to-barrel combination.
2. Incorrect Taper Crimp being applied. This can be either too much TC or too little TC.
3. Case heads being over-sized from brass being fired in weapons with loose chamber dimensions, OR case heads being expanded from being fired using high pressure rounds, such as "Major PF" rounds used in "9mm Open" guns. In many CZ pistols case heads larger than 0.391" simply will not enter the chamber.

Reloading is more Science than Art, and as such each of these can be diagnosed with simple Tests and Measurements. It's not "rocket science", but extreme care and precision is required.

Here it's important to note that reloading is not Art in the sense that simply looking for bulges or "things that don't look right" will never solve your problem. This is Science and you MUST measure and allow the measured dimensions to prove or disprove. This is exactly why each reloading manual has a cartridge diagram.

Supporting methodologies for diagnosis and diagrams to explain are already in the Stickies and there is no need to replicate those here.

Hope this helps.

[M1A4ME]

After you've resized the case, but before you do anything else to it, remove the barrel and drop some cases into the chamber.  Like a good plunk test, do you hear it (case mouth) hit the end of the chamber area specifically cut for the brass?  If a freshly resized case (or 10) won't go in completely there's no use continuing your normal reloading steps.

You've got a die, die set up, or bad brass issue.

People reloading their ammo to such high pressures that they can get their 9MM to compete in classes favoring larger/heavier bullets has resulted in brass issues that a standard die can't always correct.  Now such things as push through resizing dies (so it gets the whole case from case mouth all the way to the bottom of the case next to the extraction groove and another resizer that rolls the brass between multiple steel rollers to return the brass case near the rim to original diameter.  Even then most of the guys using those loads won't continue to reload their brass multiple times like the rest of us.

Very seldom, in 40 plus years of shooting my reloads have I found the best accuracy (smallest groups) at the maximum powder charges/highest bullet velocity.  Good groups and reliable function and reduced wear/tear on your pistol/rifle is usually 100 to 150 fps below the max. listed.  Has been for me.

One more thing.  Get yourself a reloading data logbook.  Or use a spreadsheet.  But record the information you used/measured to make your reloaded ammo.  That way you can always go back to check what worked, or didn't work, if you get into problems later.  To tie that ammo to the log book I use a small piece of paper with a copy of the information for that ammo placed into the box or the ammo can, etc. 

[bonj]

CZ warranty reply for my CZ 75B Omega:
Based on the wording it appears correct, they could not find any issues normally with the firearm. They confirmed the function but also lengthened the chamber throat to allow the fitting of larger than standard ogive ammunition as mentioned in the latter part of the Gunsmith’s notes.

As the request was written and added to the RMA, your words were: “The firing pin tip is not visible in the slide if you push on the firing pin at the rear of the slide.” The Gunsmith confirmed the firing pin was normal with no damage and added that information to the case notes so that there were no misunderstandings.
                                                                                                                                                                                                                                       
However, based on no issues being found with the firing pin the only other possible issue that would prevent the firing pin from contacting the primer would be due to the slide not being fully closed. When this occurs it is usually from larger than standard ogive ammunition, or cases being slightly too long for this C.I.P.(European standard) dimensioned chamber.

This is a common mistake those who don't fully understand the operation of the machine make. Simply pushing the firing pin from the rear will not allow it to move into the chamber unless the firing pin block is depressed as well to release it. Hence the reason the gunsmith found no issue with it.

CZ warranty reply for my CZ 75B Omega:
As for your 2nd question, it is unlikely that a stainless guide rod would resolve any issues of that nature, they would more likely instead cause issues with feeding from the increased friction.

Not sure who came up with this but it is incorrect information. The steel guide rod will not increase friction in any way. They are a common upgrade and CZ even has sold them in the past. Never had any issue of any kind with a steel guide rod in any of my CZ's or any other gun that I added them to for that matter.

CZ USA has never provided a SS guide rod, per the CZ warranty Dept, maybe the other related sights, that are not
the same, have though.

[SI VIS PACEM PARRABELLUM]

CZ USA has never provided a SS guide rod, per the CZ warranty Dept, maybe the other related sights, that are not
the same, have though.

No sir you are either wrong on your own or being given incorrect information by someone who is unfamiliar with the CZ parts dept. Here is the link for the compact guide rod which is out of stock at this time.
https://shop.cz-usa.com/custom-stainless-guide-rod-compact19195.html

[FTMFXR]

Case gauges are a good tool but so is the barrel the ammunition is to be fired in.

[gifbohane]

I suffered the same problem and spent a lot of time playing with the barrel plonk and OAL. I did send it back to CZ and I had good results since.