JMR1121
Active Member
Make sure your rails are well lubricated as well.
Which spring? The follower spring or the recoil spring? I am figuring the follower spring.
The malfunctions are likely due to cheap ammo. What ammo were you shooting?
The dislodging of the top round in your mag is a partialfeed. This is a fairly common issue with new CZs. 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 Stuart @ CZ Custom Gunsmithing). The area to be beveled is shown in red and the area to be polished is shown in yellow.
Make sure you understand exactly what "polishing" and "bevel" mean in the context of gunsmithing. You can always remove more metal, but you can never replace it if you take away too much.
CZ's aren't much different than any other pistol. They have ammo they like and ammo they don't like. All of mine seem to prefer 124gr FMJ over 115gr and 147gr. My 75B definitely prefers brass cased 124gr. FMJ and I've had no issues with any of the brands other than Fiocchi, which functions just fine in all my other CZ's.
I would clean it up, lube it up and put at least 1000 rounds thru it before doing anything, unless the problem starts getting worse. You don't have to run a 75 as wet as a 1911 but, it does like a generous amount of lubricant on the slide and frame rails. I use FP-10 but there's plenty of other good ones out there.
Update - Went to the range Saturday, 28 degrees..1st mag Speer Lawman 115gr, 2 FTE’s, 2nd mag S&B 115gr, 2 FTE’s, 3rd mag Aguila 124gr, no FTE’s, went through 3 boxes flawlessly, went back to the 115’s and again, no FTE’s. Going again this weekend and start cold with the 115’s and see if things have worked themselves out.