Author Topic: CZ75b failure to eject using 16rd CZ mags.  (Read 976 times)

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Online Rmach

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CZ75b failure to eject using 16rd CZ mags.
« on: March 12, 2019, 08:21:00 PM »
Not a big problem, but I experienced 4 FTE's out of 500rds in my last two visits to the range with my plain Jane CZ75b that had no problems previously using mostly 17rd mags.  This time, same 115gr Speer ammo, I only used the factory CZ 16rd flat base mags on the first visit and added a 17rd Mecgar mag on the second visit.  The 16rd mags failed twice each (2 rounds with stovepipes) after the first 150rds. The 17rd mag didn't have an FTE.  Today, the third 250rd range visit, I only used two 17rd mags and had zero FTE's, including the last 30rds of rapid fire. Just thought this was interesting and wanted share the experience. It seems the 17rd Mecgar mags are more reliable on this particular CZ75b.  The feed lip measurements are identical on both 16rd and 17rd mags, but the follower angle is slightly different.
« Last Edit: March 12, 2019, 08:27:59 PM by Rmach »
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Offline himurax13

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Re: CZ75b failure to eject using 16rd CZ mags.
« Reply #1 on: March 12, 2019, 09:07:40 PM »
Not a big problem, but I experienced 4 FTE's out of 500rds in my last two visits to the range with my plain Jane CZ75b that had no problems previously using mostly 17rd mags.  This time, same 115gr Speer ammo, I only used the factory CZ 16rd flat base mags on the first visit and added a 17rd Mecgar mag on the second visit.  The 16rd mags failed twice each (2 rounds with stovepipes) after the first 150rds. The 17rd mag didn't have an FTE.  Today, the third 250rd range visit, I only used two 17rd mags and had zero FTE's, including the last 30rds of rapid fire. Just thought this was interesting and wanted share the experience. It seems the 17rd Mecgar mags are more reliable on this particular CZ75b.  The feed lip measurements are identical on both 16rd and 17rd mags, but the follower angle is slightly different.
I recommend replacing the springs with the wolff +10% springs. That and a good cleaning should fix your issue.

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Online Rmach

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Re: CZ75b failure to eject using 16rd CZ mags.
« Reply #2 on: March 12, 2019, 10:06:02 PM »
Not a big problem, but I experienced 4 FTE's out of 500rds in my last two visits to the range with my plain Jane CZ75b that had no problems previously using mostly 17rd mags.  This time, same 115gr Speer ammo, I only used the factory CZ 16rd flat base mags on the first visit and added a 17rd Mecgar mag on the second visit.  The 16rd mags failed twice each (2 rounds with stovepipes) after the first 150rds. The 17rd mag didn't have an FTE.  Today, the third 250rd range visit, I only used two 17rd mags and had zero FTE's, including the last 30rds of rapid fire. Just thought this was interesting and wanted share the experience. It seems the 17rd Mecgar mags are more reliable on this particular CZ75b.  The feed lip measurements are identical on both 16rd and 17rd mags, but the follower angle is slightly different.
I recommend replacing the springs with the wolff +10% springs. That and a good cleaning should fix your issue.

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Thanks, but I did clean the 16rd mags internally before both outings, and the spring tension seems the same using my thumb as a proxy.
CZ Shadow 2 Orange, S2 urban gray, S2 black and blue, 3 polished stainless 75b's and a black 75b all with MCARBO kits and front Dawson FO.

Offline himurax13

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Re: CZ75b failure to eject using 16rd CZ mags.
« Reply #3 on: March 12, 2019, 10:48:02 PM »
Not a big problem, but I experienced 4 FTE's out of 500rds in my last two visits to the range with my plain Jane CZ75b that had no problems previously using mostly 17rd mags.  This time, same 115gr Speer ammo, I only used the factory CZ 16rd flat base mags on the first visit and added a 17rd Mecgar mag on the second visit.  The 16rd mags failed twice each (2 rounds with stovepipes) after the first 150rds. The 17rd mag didn't have an FTE.  Today, the third 250rd range visit, I only used two 17rd mags and had zero FTE's, including the last 30rds of rapid fire. Just thought this was interesting and wanted share the experience. It seems the 17rd Mecgar mags are more reliable on this particular CZ75b.  The feed lip measurements are identical on both 16rd and 17rd mags, but the follower angle is slightly different.
I recommend replacing the springs with the wolff +10% springs. That and a good cleaning should fix your issue.

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Thanks, but I did clean the 16rd mags internally before both outings, and the spring tension seems the same using my thumb as a proxy.
Upgrading the springs sounds like the next logical step then. One variable at a time.

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Offline ZanderMan

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Re: CZ75b failure to eject using 16rd CZ mags.
« Reply #4 on: March 12, 2019, 10:58:09 PM »
Dunno, hard to imagine why a mag could cause FTE.

It?s not even involved in the ejection process. You should be ejecting properly with NO mag installed.

Check your extractor tension / claw cleaniness, it could be coincidental on the mags.
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Online Rmach

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Re: CZ75b failure to eject using 16rd CZ mags.
« Reply #5 on: March 13, 2019, 05:41:58 AM »
Dunno, hard to imagine why a mag could cause FTE.

It?s not even involved in the ejection process. You should be ejecting properly with NO mag installed.

Check your extractor tension / claw cleaniness, it could be coincidental on the mags.

Before the second range trip, I checked the spring tension and thoroughly cleaned and inspected the extractor.  Were tallking 4 FTE's out of 500rds. I used two 16rd mags on the first trip with 2 FTE's from the same mag. On the second trip, I used the good 16rd mag from the first trip and one 17rd mag. The good 16rd mag produced two FTE's between 120-150rds. At that point, I finished off the balance of the 250rds using just the 17rd mag with zero failures. That's why I only used 17rd mags for the third 250rd range visit which had no malfunctions.  Too much evidence to be a coincidence IMO.
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Offline Tyerone

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Re: CZ75b failure to eject using 16rd CZ mags.
« Reply #6 on: March 13, 2019, 06:26:19 AM »
Everyone can always make room for a couple new magazines,  Time to buy a couple more, I suppose.  Then depending on round count change some springs.  Recoil spring?  Are casings just dribbling out when ejecting?

Offline Walt Sherrill

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Re: CZ75b failure to eject using 16rd CZ mags.
« Reply #7 on: March 13, 2019, 09:38:02 AM »
FTE can mean a failure to EXTRACT or a failure to EJECT.... which was it?

I'm like Zanderman -- I don't understand how a magazine can affect or cause extraction problems UNLESS the upward pressure of extra-power mag springs are causing the top round in the mag to press against the underside of the slide, slowing it down.  It would also be less noticeable as fewer rounds remain in the magazine.  (If the 16-round mag springs are new/recently replaced, try them with a few less rounds to see if that helps.  The springs will slowly take a set and degrade a bit.)   Otherwise, a mag spring doesn't seem a likely cause for what you describe. 

When other mags work well, it's logical to assume it's a mag issue -- but it could simply have been ammo issues. too. 

I used to have a lot of problems with Winchester White Box... the design of the case, back then, didn't let the extractor get a good, consistent purchase on the case rim.    I never noticed a problem with some magazines and not others, but I just avoided WWB  like the plaguel Winchester seems to have fixed that problem and the case rim is different now. (I still avoid it.)  Cheap ammo often gets fewer QC checks than the pricier stuff, so some variance in performance is possible.

Some years back, a bunch of CZ owners here on the forum found that going with a Wolff extra-strength extractor springs helped a lot, and CZ later upgraded that spring in the new guns.  If you have an older CZ, a new extra-strength extractor spring might help.   

I'll be interested in learning whether there is another (magazine-related) solution to this problem.   I continue to learn new things.

Offline M1A4ME

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Re: CZ75b failure to eject using 16rd CZ mags.
« Reply #8 on: March 13, 2019, 10:37:58 AM »
Wild thought here.....Some people report their pistol dragging the top round in the magazine forward as it chambers what was the top round.  Could the tip of the bullet, after being dragged forward, contribute to your issue if the case being extracted from the chamber hits it prior to the ejector?

That would deflect the empty case at a different angle than normal.  I haven't checked any of mine to see if that top round can be that far forward, or that high, so I can't say for sure one way or the other.

I also don't remember if there was a "fix" for that top round being dragged forward.  Some of my pistols do it a little bit, some don't seem to do it at all.  Of course, where people reported that problem what they were experiencing was the tip of that bullet dragging on the front of the mag. well/feed ramp area and making it harder to remove a partially loaded magazine.

Would new/stouter magazine springs contribute to keeping the top bullet from being dragged farther forward as the slide drags across it?

One other thing I'd look at, since you see this issue on 16 round but not 17 round magazines is - if you lock the slide to the rear and insert a loaded magazine, does the angle of the top bullet look different in the 16 round vs. 17 round magazines.  Doesn't mean the feed lips are wider/narrower/bad, just wondering if some combination of the follower, spring pressure and feed lips results in a different angle on that top bullet.
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Online Rmach

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Re: CZ75b failure to eject using 16rd CZ mags.
« Reply #9 on: March 13, 2019, 11:34:16 AM »
Wild thought here.....Some people report their pistol dragging the top round in the magazine forward as it chambers what was the top round.  Could the tip of the bullet, after being dragged forward, contribute to your issue if the case being extracted from the chamber hits it prior to the ejector?

That would deflect the empty case at a different angle than normal.  I haven't checked any of mine to see if that top round can be that far forward, or that high, so I can't say for sure one way or the other.

I also don't remember if there was a "fix" for that top round being dragged forward.  Some of my pistols do it a little bit, some don't seem to do it at all.  Of course, where people reported that problem what they were experiencing was the tip of that bullet dragging on the front of the mag. well/feed ramp area and making it harder to remove a partially loaded magazine.

Would new/stouter magazine springs contribute to keeping the top bullet from being dragged farther forward as the slide drags across it?

One other thing I'd look at, since you see this issue on 16 round but not 17 round magazines is - if you lock the slide to the rear and insert a loaded magazine, does the angle of the top bullet look different in the 16 round vs. 17 round magazines.  Doesn't mean the feed lips are wider/narrower/bad, just wondering if some combination of the follower, spring pressure and feed lips results in a different angle on that top bullet.

You hit on a few things that do apply to my failure to extract.  I would have called all four of them stovepipes, but the empty cases were not standing straight up but were jammed more parallel to the slide. Each failure did move/drag forward the next live round jamming it under the spent casing.

Also, there is a slight feed angle difference between both 16rd mags when compared to the 17rd mags. If you load 5 rounds or so into the 16rd and 17rd mag, you can then see the slight angle difference between the two. The mag feed lip opening on all four mags measured the same with my caliper, and the mag spring tension felt the same.

Each failure happened on round 5-8 in the 16rd mags, so not the first or last round.  This particular case of 115gr Speer Lawman left some heavy powder residue in this factory stock 2016 CZ75b. Oh, the ejections are not weak.

Here's a pic I found online that resembles the problem. This pic does not show the next round that moved forward in the mag as it did in my case.



« Last Edit: March 13, 2019, 01:56:10 PM by Rmach »
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Online Rmach

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Re: CZ75b failure to eject using 16rd CZ mags.
« Reply #10 on: November 06, 2019, 12:22:13 PM »
Update on this.  I put in a 13# recoil spring in this black 75b to see if that would make a difference with that occasional failure to eject/stovepipe/extract with the 16rd mags only. Each of the two 16rd mags that I used produced one malfunction in 100rds yesterday.   Remember, the 17rd mags produced no malfunctions in a 1000rds, only the 16rd mags did.

Anyway, I took a few pics of the bullet angles from the 16rd mag and the 17rd mag. The angles and height  are different as seen in the pics. This has to explain why the 16rd mags produce this 1% malfunction rate in this particular CZ75b. I laid a flat paint scraper on the frame rail so you could see the height of the tip more easily than the side pics.

16rd mag:


17rd mag:


16rd mag:


17rd mag:
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Online Rmach

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Re: CZ75b failure to eject using 16rd CZ mags.
« Reply #11 on: November 06, 2019, 02:23:04 PM »
I just found this post from 2009 on the web:

When chambering a round, the underside of the slide behind the breech face can drag on the next round at the top of the magazine.  This can partially dislodge the next round from the magazine.   The partially fed round may end up sitting with its nose at the bottom of the feed ramp and interfere with the extraction/ejection of the chambered round.  In addition, the partially fed round can cause the magazine to hang if you attempt to drop the magazine.  To alleviate these problems, the lower (leading) edge of breech face should be beveled and the underside of the slide behind the breech face should be polished.  These modifications are shown in the following photograph (courtesy of eerw).  The area to be beveled is shown in red and the area to be polished is shown in yellow.


I checked the bevel on my other two stainless 75's, and they had more bevel than this black 75 does on all three edges, and it was rougher so that my finger nail could catch the edge, so I broke out the file and 1000 grit to increase the bevel ever so slightly, not quite as much as the other two 75s but more than it was originally. I polished the remaining tract with the same 1000 grit. I have no idea if this will stop that 1% failure rate that happens only when I use the 16rd mags.
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Online Rmach

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Re: CZ75b failure to eject using 16rd CZ mags.
« Reply #12 on: November 07, 2019, 06:30:49 PM »
Went to the range today with the same handgun and ran another 200rds (same American Eagle) with zero malfunctions using the 17rd mags only. Sometime in the near future, I'll try the 16rd mags again to see if beveling and polishing on that third rail helped.
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Offline DenStinett

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Re: CZ75b failure to eject using 16rd CZ mags.
« Reply #13 on: November 07, 2019, 10:55:45 PM »
Try reducing the Spring Angle at the front of the Magazine Spring
You know how everyone bends the front of the Mag Spring up
Try doing just the opposite to the Springs in your 16 round Mags
Worth a shot !
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