Glock mag malf

[kevin c]

Just an FYI:

I have several ten round mags that I use in my Production G34, seeing as they work well and I can spare my std cap mags the wear and tear (yes, I know and have gotten replacement parts for my std cap mags here in California, but sometimes the hassle factor interferes). These venerable mags have the original springs, and run my 135 PF load just fine.

I got a new stock G34 recently, and used my match load in these same mags to test it out. The gun gagged on almost every round, always with the same feeding malfunction - the case would eject, but the next round would hang up, jamming the slide just forward of the locked back position. The view through the ejection port shows the round partly fed out of the magazine, but with the case head and extractor rim of the cartridge still below the base of the breechface. AAMOF, the base of the breechface, the part that strips the round out of the magazine, was usually jammed right into the extractor rim.

I swapped out the top ends of my current G34 competition gun with the stock gun and the old slide on the new receiver ran fine. I swapped out the 17# standard recoil spring in the new slide for the 11# ISMI in the old one (same std plastic guide rod in each) and the light spring in the new slide worked fine.

Ran it by the Glock armorer at the GSSF match we held this past weekend (new northern California record for entries! ), and he and I both think the same - old mushy mag springs unable to keep up with the more rapid slide cycling of the new #17 recoil spring assembly. Interesting to note that the 11# spring is pretty ancient too. I may have had a case where all the old springs fortuitously weakened together but complemented each other. Might be that a new 11 or 13# spring would have made the gun choke with the old mag springs. Got new springs and will test them out in both the old and new guns this weekend. I'll also replace the recoils spring and see if that screws with a weak springed mag.

Also found an old thread of mine where I had a similar problem but with a less definite cause (though the ultimate disposition there was that I pushed up the PF to 135):

http://www.brianenos.com/forums/index.php?showtopic=49920&st=0

For your eddy-fee-kayj-shun/eddy-kay-shun...

Edited August 29, 2012 by kevin c

[ProGunGuy]

sounds like you may have figured it out. Did you change the followers also. the latest ones to use are 9mm/2 followers.

[Braxton1]

Yep, I think you've got it.

Having the stripper rail over-ride the new cartridge is a classic sign of a VERY weak mag spring.

[RaylanGivens]

sounds like you may have figured it out. Did you change the followers also. the latest ones to use are 9mm/2 followers.

How can you identify the 9mm/2 followers?

I looked in my most recent Parts List and found two available 9mm followers... an older 9mm 3 follower that Glock calls original style and a 9mm 6 that Glock calls cap style fits ONLY mags factory supplied w/ "4", "5", or "6" followers and Gen 4. The 9mm 6 followers seem to have a "6" molded in to the top, visible part of the follower.

As a point of interest, since the original poster mentioned issues with his 10 round magazines... Glock also lists a separate 10 round follower..."9mm 10-rd G17-G19-G34 mags only" It doesn't say what the different is of course, but Glock wouldn't make a separate follower if the standard ones would work.

[RaylanGivens]

Yep, I think you've got it.

Having the stripper rail over-ride the new cartridge is a classic sign of a VERY weak mag spring.

Not sure what you mean by stripper rail... Do you mean the center part of the slide that pushes the round forward out of the magazine?

[Nik Habicht]

Kevin,

I agree -- probably time for some new mags, or at least springs. My theory is always that by the time the springs are worn out, there are enough burrs on the mag bodies, that replacing them just makes sense....

I've had 3 34s, two of which would only run reliably with a 13 lb. spring, the third of which I was able to get down to running with 11 and 12 lb. springs. Sometimes the parts tolerances just stack up in a funny way, and what runs in one gun, won't run in another....

[ProGunGuy]

sounds like you may have figured it out. Did you change the followers also. the latest ones to use are 9mm/2 followers.

How can you identify the 9mm/2 followers?

I looked in my most recent Parts List and found two available 9mm followers... an older 9mm 3 follower that Glock calls original style and a 9mm 6 that Glock calls cap style fits ONLY mags factory supplied w/ "4", "5", or "6" followers and Gen 4. The 9mm 6 followers seem to have a "6" molded in to the top, visible part of the follower.

As a point of interest, since the original poster mentioned issues with his 10 round magazines... Glock also lists a separate 10 round follower..."9mm 10-rd G17-G19-G34 mags only" It doesn't say what the different is of course, but Glock wouldn't make a separate follower if the standard ones would work.

sorry, looked closely and they are 9mm/3 followers. i have them installed due to problems i was having with the originals in my 10rd mags. they work just fine in the 10rd mags.

And glock does make a separate follower for the 10rd mags for some reason

Edited August 31, 2012 by ProGunGuy

[kevin c]

hmmmm...

The new springs in the mags didn't help. Same malf with the new upper w/ the std recoil spring.

The load, at about 135 PF, is apparently too light for the std 17# spring, making the gun short cycle. The same load will run in a G17 with the std recoil spring. That 17 will run 124 PF loads that I made up as calibration loads, where my light springed G34 won't. Even with the slide lightening cut out, I guess the mass of the 34 slide combined with the light spring is too much. Gotta use an 11 or 13 pound ISMI.