P-07 failure to feed…sometimes

[Butters]

Okay guys, thanks for having me - first time post and new member, own a few CZs.

So I’ve had my P-07 for about a year; I have a defensive Cajun gun works package on it except the hammer and short reset lifter and disco…everything else has been swapped out.
I also use CGW 15# recoil spring and SS guide rod.

The gun runs flawless with the 15rd mags, runs like a champ.
I wanted to increase capacity so tried out the +2 CZ plastic extension and the shield arms +5 which is shipped with a spring.

The gun will have a failure to feed about 6 or so rounds into the mag with both extensions. At first I thought it was the factory spring so bought a CZ Custom 17rd spring to use for the +2 - same thing happened. I took the +2 off and put them back for when my P10S comes in. Later on I tried the shield arms extension and used the spring they sent me. Same thing, about halfway thru the mag FTF.

The gun runs smooth as butter with factory 15rd mags…am I missing something?

Any suggestions would be really helpful - not sure if I should swap back the recoil spring and guide rod to factory or what. Or maybe I need to work in the springs more? Tension seems good, although the shield arms seemed kinda tight but I haven’t had it that long - I haven’t had a lot of time to go to the range to mess with things but just wanted to reach out to see what y’all thought about this. Again, the gun never has any issues at all with 15rd mags, only seems to have increased FTF issues with extensions added even with proper sized springs are also used.

Open to suggestions- thanks.
I’d post a picture of it but need to figure out how to upload from my iPhone, new to this forum 🤦🏻

[CCWLearner]

Hello, and welcome to the forum and the polymer pistol sub-forum.

I have two P-07's which were purchased new in 2017 and 2018.  They are set up very similar to yours, except I do run the CGW hammers, but with factory firing pins.  I have run the 15# recoil spring with their SS guide rod in the past, and currently am running their 18# spring on a titanium alloy guide rod I got to reduce the carry weight of my pistols.

My pistols are rock-solid reliable when it comes to feeding all of the ammo I shoot, out of every type of magazine I own, which includes factory 15-round mags with various +0 base pads, including original factory P-07 polymer pads and some aftermarket aluminum ones, also including some with the factory +2 polymer base pads using the original springs.  I have no experience with the Shield Arms +5 extensions, but I did order some of their extra strength springs and test them in my existing mags with 100% success, just to have some spares in case of failures in the future.  I also have some spare OEM followers I ordered from HB Industries in case of follower problems which I haven't had.

Anyway, I have one pistol with probably 3-4K live fire and another around 4-5K of live fire and the vast majority of that live fire in both has been through three designated range mags I use with aftermarket aluminum +0 followers... haven't had a single issue with any of them yet.  I do break them down and clean them periodically, and use Eezox on the bodies and springs for a dry lubricant and rust protectant... but I also never had a problem from them when they were dirty and/or I was running them bone dry.  As for the +2 adapters installed I have tested them quite a bit with both range and defense ammo with zero issues.  I find them a bit bulky for CCW but I keep one loaded in my nightstand with my spare 15-rounder and consider it 100% reliable.  Like my other carry mags, it doesn't see much range time on an ongoing basis but it has never failed when dumping old defense ammo periodically.

Don't have any really good suggestions for you because I haven't figured out how to induce a failure like the one you describe.  I don't think your guide rod or recoil spring would be a problem, but you could try that.  You have already tried different mag springs.  I don't see where you mentioned what ammo you are shooting but obviously you should try to induce the failure with multiple types to rule that out.

[Butters]

Thanks for the advice, info and welcome CCWLearner..
As far as ammo, when this has happened it’s been typical range ammo. federal one time for sure, I’d say probably Winchester white box the other time 115-124gr. Although I’ve had this P-07 a year give or take with the guns and projects I’ve been working on I don’t always take it with me so only have about 500rds thru it. Maybe it’s just the magazine springs still being new - I leave them empty when not using them. For instance, my carry guns will have a loaded magazine and the spare mags will be empty, once a week I’ll unload the mags and rotate them out and so on etc. Spare magazines I carry with me are emptied when I get back home.
I’ll continue to mess with it, how did you like the 18# spring to the 15#? I forget what the factory spring is at but I was going back and forth on which to get and Cajun recommended with my setup to get the 15 pounder. The hammer will be the next and final thing for my P-07, I’ve just been busy with other projects to get it.
Just baffles me that this piece shoots so well and then gives me issues with magazines that have extensions.
Thanks for your help again, appreciate it.

[M1A4ME]

Have you tried P09 magazines?  19 rounds out of the box.

That's what I use for my P07 9MM for spare/back up mags.  Well, the 19 round factory mags. with the +2 bases on the bottoms.  So 21 rounds, really.

Sounds like, at a certain point in upwards position of the follower/spring/rounds you're getting either a change in movement speed or angle of the rounds moving up.  Have you cleaned the insides of the magazines and spring/follower?

Also, stripping the oil off and waxing the insides/outside of the magazine will make loading/feed from the magazines slicker.  Two coats of carwax applied/buffed off just like you would on your car, will give you a noticeable improvement in how smoothly ammo loads into the magazine (so it should also be smoother when the spring is pushing the rounds up to the top.)  Plus, waxing seems to keep the magazines cleaner and any water/dirt/dust that does get on them wipes off quick/easy with a dry cloth.

[CCWLearner]

I’ll continue to mess with it, how did you like the 18# spring to the 15#? I forget what the factory spring is at but I was going back and forth on which to get and Cajun recommended with my setup to get the 15 pounder. The hammer will be the next and final thing for my P-07, I’ve just been busy with other projects to get it.
Just baffles me that this piece shoots so well and then gives me issues with magazines that have extensions.
Thanks for your help again, appreciate it.

I think the 15# spring improves the DA pull noticeably over the 18# spring.  CGW recommends the 18# spring for carry/defense and the 15# spring for regular range use, with weaker springs for competition and a limited selection of primers.  In my two particular pistols the 15# springs have proven to be 100% reliable with all of the ammo I shoot, using the factory firing pins, so I carry with them.

I think M1A4ME's theory about how the mag was seated sounds like a possibility.  Although I would expect that to be more likely with using P-09 or P10-F mags than with bases designed to fit against the grip of the P-07.  Certainly cleaning them out good won't hurt and is probably a good idea anyway, along with possibly using wax or some type of dry lube on them.  I'd use alcohol or acetone to clean any remaining factory oil and gunshot residue out to start with.

Another thing I'd probably try, if you have enough snap caps on-hand to do it, is to cycle them manually through the gun at home and see if I could induce the failure.  I don't personally have 17 9mm snap caps handy so I'd have to order some more.

[M1A4ME]

How are the springs made?

I ask due to an issue I had with my P14 years ago.  It would stop feeding from the magazines (all factory mags) part way through when thumbing them out to empty them.  Never did while firing.

I took them apart the springs were dirty, as was the inside of the magazine body.  Then I noticed the spring were made "funny" vs. every other spring I'd ever seen in a magazine.  Near the center of the spring the coils were smaller, so the coils in the middle nested down inside the larger coils at the top/bottom of the springs.

Just for the heck of it I ordered new springs and they were made different.  Same diameter coils top to bottom and no more rounds hanging up part of the way through the stack while thumbing them out.

Made me wonder if recoil jostled the springs enough to unbind them while firing, but with no recoil the coils were hanging up inside the bigger coils when just thumbing them out.

Not saying your CZ mag. springs are made like the original P14 mag. springs, just saying weird stuff can happen and sometimes taking stuff apart and cleaning it helps you see something you didn't notice prior.

[Butters]

Thanks for y’all’s help - I packed the 20 rounds and left it loaded for almost 2 weeks and took it to the range, functioning fine. I haven’t tried the +2 cz extensions bc I’m using those for my p10s but those are working fine. I guess the springs weren’t fully worked in on the shield arms or the czc 17 round springs.
Thanks for the help and suggestions