Sent it in because the slide was locking back while there was still ammo in the magazine.  Turn around time was good, a little over 3 weeks, but I'm disappointed that there was no communication from them between the time they received it and the time they shipped it back.  Also, I cleaned it before sending it back and it came back clean, so either they cleaned it themselves or they didn't shoot it much, or not at all.













 

You have to keep after CZ to get any info, but it sounds like they sent you a note with what was done.
My 07 has been back twice now, first time they sent a new pistol to replace the one that had a frame bulge around the metal frame inserts.
That 07 ran great for 800 rds, then developed a very heavy single action pull.  Like 20# heavy, D/A worked normally.
CZ gets the pistol and finds nothing wrong, and sends it back.  I have no idea what happened in transit, but there must have been something going on.  Pistol is now back to me, it is working properly.  The smith at CZ said they had no idea what could be wrong.
 I really like it,and feel it would be a great CCW piece, but I would want to replace the sights and figure out why it had the heavy SA pull before I trusted it for CCW.   I'm prolly going to sell the 07 and buy a second P01.  Or a LW commander.

I took the P07 back to the range yesterday with 100 of my semi hot handloads (each checked in a chamber gauge), 100 factory rounds (Tula this time) and I also had 30 old 124 grain Speer Gold Dots that I've had for around 10-12 years.
















 

I was having the same issue with a glock I bought when they switched to the newer style slide lock.  I realized on my thumbs up grip my off hand thumb was catching the slide lock when the recoil was coming back down.  Even though I wasn't riding the lever when I shot the recoil was enough to catch my thumb for a split second.  Just a thought.

As odd as it might sound, can you have someone videotape you shooting? See if that might be the issue with the harder recoiling Gold Dots. Random thought, have a nice day.

Well it's doing it again.  This time with a box of steel cased Wolf ammo.  Twice in 50 rounds the slide locked back while there were still rounds in the magazine.  Looking at my hand on the gun I can't even imagine how I could be coming into contact with the slide lock lever.  I think if any part of my hand was hitting it I'd be feeling it.




 

 







































 

Just curious, but have you numbered your magazines and seen if it is isolated to one magazine?

On grip:

Try one handed to see if the off hand (right in your case) is activating the slide lock on recoil.
Try one handed with your right hand, so see if (for whatever weird reason) it is your left hand pushing the slide release up.
The other thing is to gorilla grip the gun to make sure nothing is contacting the slide lock.
Can you have someone take pictures of your normal grip on the gun? From looking at pictures of the P07 online, the slide lock/release looks huge and is pretty low. I shoot thumbs high (on top of the safety) and I suspect if I shot left handed, my hand would/could easily contact the slide lock on recoil.

On bullet profile:

Also, look at the profile on the bullets, especially since the corroded (rough) Speer ammo caused the problem and the clean bullets did not.
Are the problem rounds fatter? As Maynard also asks below, what grain ammo are you using and what profile? (Flat point tends to be fatter than round.)
Sometimes the fatter profile will bump the slide lock up when feeding.
Does it happen with 124 and 148 grain but not 115 grain bullets or flat point but not round?

ETA:

Found a picture. Based on the picture at the end of this Guns and Ammo review http://www.gunsandammo.com/reviews/new-age-9-cz-p-07-duty-review/ I would certainly suspect that if you have large hands or a high grip that you're contacting the slide lock on recoil. You might buy a second slide lock and grind it down until it barely works (or doesn't work) and see what happens.

 

I'll try the different grips sometime next week.  I'll have someone take a picture later and I'll post it this evening.  With my norma left handed grip, despite it looking like my trigger finger is close to the slide release, it hits the frame well before it contacts the slide release and there's nothing I can do to make it contact it without it hurting.  














 

Check this out.  I've just been sitting here with the slide off and the slide release inserted and I noticed something interesting.  
































 

Interesting. Never heard of magazines pushing on a slide stop/release before. I suspect you figured it out.

Do you have the "old-style" mags with the glossy finish, or the new revision with the matte finish?

My P07 is the older DUTY style gun.  It's a .40 S&W.  I also have a 9MM slide/barrel/slide stop and magazines for it.

I just checked it like you did with yours, with the .40 S&W slide stop and magazine and the magazine does not contact the slide stop with the magazine in "normal" position or when pushed upwards as far as it will go.

Then, I went to the cabinet and got the 9MM parts and saw a different story.  The magazine is contacting the slide stop with the magazine in "normal" position and if I push up on the magazine it will push the slide stop up.

"Normal" is the magazine just "hanging" on the magazine catch in the mag well/grip of the pistol.

Closer examination of the slide stops shows the one for the .40 S&W is made different than the one for the 9MM.

.40 S&W (the post that contacts the magazine follower) is slightly above the cast line on the horizontal/outside portion of the slide stop and that part is also made different inside.  The post is tapered on the rear side of it (possible to clear the larger .40 caliber bullets???) so that it doesn't stick into the magazine area as far.

9MM (the post that contacts the magazine follower) is right on the cast line on the horizontal/outside portion of the slide stop.  The post is rounded and the same front or rear where it sticks into the magazine area.

Don't have a camera to take pictures, but they are obviously different.  I never paid attention to them before, just switched them back and forth on the frame depending on what caliber I was shooting.

I also don't know if possible there is a difference between the magazine bodies themselves.  The .40 S&W magazine make contact with the 9MM slide stop (just like the 9MM magazine does) so I can't say the .40 S&W magazine is different.    I can only say, for my pieces/parts, the 9MM and .40 S&W slide stops are made different.

I noticed one other thing while moving parts back and forth on mine and looking at the slide stop/magazine interaction.  Do you shoot with your support hand under/contacting the magazine?  If so you may be slightly pushing the magazine up (raising up the slide stop) when it might not contact the slide stop enough to move it upwards otherwise.  Just a thought.

@stfram - Without something to compare them to I don't know if I have the old or new mags, mine aren't really glossy, but aren't what I'd call a true matte finish either.

To OP,if your in the Phoenix area,CZ Custom is in Mesa,They have some top notch Gunsmith's there.And everything your CZ might need.
Have them have a look over it,they do have a full CZ service center.

http://czcustomguns.com/

Finally managed to get out to the range today despite the weather sucking big time and I'm happy to report that my P07 functions perfectly with the mag mod.  I put about 200 rounds though the modded mag, a mix of my reloads, Tula factory 9mm and Speer 124 grain Gold Dogs and it functioned perfectly with all of them.

Good to know you've at least tracked down the issue.
Is the fix that you are cutting the notch in the magazine deeper? By notch, I mean the location where the slide stop sticks through to contact the follower?
Just want to make sure I understand.
Also interested to see CZs response.

 

This is what I meant. I understand.


Me too. You don't want to hope to remember not to do something you do normally do, while under pressure.

That's partly why I was asking, since I don't usually do it, but it's good to know about this gun. (What if you're firing prone or from a barricade and that pushed the magazine up?)

After having written to CZ and having a friendly exchange with one of their gunsmiths my P-07 is on it's way back to CZ.