Glock 33-Round Magazine Deformation?

[StealthyBlagga]

I ran one of my PCCs in a match on Sunday, and on the last stage had several feeding malfunctions. The gun is a frankengun AR9 build with CMMG Guard barrel/bolt in a Gibbz side-charging upper on a generic (JoeBob = NFA?) lower. It is is newish - probably less than 1000 rounds fired - but has been used in several matches since break-in and has run flawlessly.

 

My first assumption was that it was just too dirty because I have not cleaned it since building it - I have just been running it to see how far it can go before malfunctioning. This may still be the root cause of the problems, but when I went to clean the magazine I also noticed the front of the tube is deformed to the point where it is hard to even insert it in the magwell. The photo below shows this particular magazine (left) next to a nearly-new magazine (right). Both are Glock 33 rounders, the deformed unit having a TF +10 extension. To muddy the waters a bit more, these mags have been used previously in another AR9 PCC (a QC10 factory gun, conventional blowback).

 

Has anyone else encountered this phenomenon? Any ideas on root cause? Any reason I should not just bend it back and keep using it?

 

[Patrick Scott]

Happens in my QC10 lower gun as well with both Taccom and JP bolts. I think its rounds that present low and hang up on the mag body. I have one mag that sees use 98% of the time and is about 10 years old. I just keep pounding the it back straight when I notice it bending out. Done that half a dozen or so times. 

[brix]

I have a QC 10 lower too and had the same thing happen using a borrowed TF base plate. I figured it was me slamming the mag into the bolt during the match which I was doing a little more violently to get the mag to seat properly. I just straightened it up and got a mbx mega ext for my next match. Two matches later haven't seen the problem since. I'm running a FoxTrot Mike upper.

Sent from my SAMSUNG-SM-G935A using Tapatalk

[StealthyBlagga]

OK, sounds like I just need to beat it back into shape. Thanks for the quick answers. 

[dlightning]

Can you repost a pic from the front?  I want to see it more clearly.

[StealthyBlagga]

10 hours ago, dlightning said:

Can you repost a pic from the front?  I want to see it more clearly.

 

Here you go - the deformation is on the front face of the tube about 5mm wide and centered on the mold parting line.

 

[Davidp1911]

Dragging bolt face...maybe?

[RaylanGivens]

I have a QC10 lower...  My main magazine is a Glock 33 rounder with a TF base plate...  No signs of a mark or protrusion yet.

 

How could a base plate adapter cause this?

[practical_man]

18 hours ago, RaylanGivens said:

I have a QC10 lower...  My main magazine is a Glock 33 rounder with a TF base plate...  No signs of a mark or protrusion yet.

 

How could a base plate adapter cause this?

 

The mag is inserted into the lower at an angle. Adding length and weight changes the center of moment and levers the front of the magazine upward when it is full; slowly changes as rounds are removed. 

 

Pushing magazine upward may allow bolt to impact front of magazine when stripping rounds  during early firing. Sort of like over insertion forces the magazine against bolt beyond the limits of mag catch to stop it. 

 

This is probably a case case of tolerance stacking. A little loose on magwel dimensions and mag catch recess a little small (or mag catch on magazine a little large). Add a magazine that’s a little small front to rear. It’s possible for mag to shift enough to bump the bolt and drag to deform the polymer. 

 

Hard to tell without the piece in hand to measure and test. 

Edited July 18, 2018 by practical_man

[RaylanGivens]

4 hours ago, practical_man said:

 

The mag is inserted into the lower at an angle. Adding length and weight changes the center of moment and levers the front of the magazine upward when it is full; slowly changes as rounds are removed. 

 

Pushing magazine upward may allow bolt to impact front of magazine when stripping rounds  during early firing. Sort of like over insertion forces the magazine against bolt beyond the limits of mag catch to stop it. 

 

This is probably a case case of tolerance stacking. A little loose on magwel dimensions and mag catch recess a little small (or mag catch on magazine a little large). Add a magazine that’s a little small front to rear. It’s possible for mag to shift enough to bump the bolt and drag to deform the polymer. 

 

Hard to tell without the piece in hand to measure and test. 

 

Interesting...  Thanks...  I usually load my 33+TF magazine to 35 rounds of so...  Almost never over 38...  Perhaps that's why I haven't seen the problem...  Plus my rifle and magazines are all pretty new...  Around 1,500  rounds or so on them at the moment.

[zeroryde]

This literally happened to me last month during a match and rounds kept on jamming. I thought it was due to a dirty mag since the range is mostly sand. I have a match tomorrow and was going to bring the pcc out again and decided to practice reloads last night. I found out my mags weren't ejecting and I had to pull them out. I decided to load one into my G34...and it wouldn't even fit...then I saw the same time and i tapped it back into place with a small nylon hammer. I wonder if it's dragging on the bolt... I have a frankenbuild Spike's lower and stripped upper with a faxon bolt and JP barrel.

[zeroryde]

Forgot to mention this happened on all my Glock mags... 33rd, 17rd and 10 rd

[gdcguns]

I have this same deformation on all my glock mags that are used in my PCC.  Like others have said, I just press it back straight and keep shooting.  Haven't seen it cause any significant issues. 

[TeamGE]

If the lower receiver does not have a support for the front of the mag, a nose dive (or a nose up miss-feed), will push that part of the mag tube forward and bend the tab. It can be straightened, but usually it will break off after 3 or 4 times. The mag was not designed to be a feed ramp, and needs a front wall to support it.

 

 

Edited October 12, 2018 by TeamGE

[TRUBL]

DILLY DILLY Beven!!! No support means that the mag can blow out the front!!! FYI.....the new TACCOM Extreme feed barrels have a patent pending feed ramp that supports the front of the Glock magazines. No more potential blow outs....breakages!! Good to see that you are still alive old friend!!

 

Tim

 

PS.......Also, people that use the TACCOM Glock feed ramp are not only getting positive feeding, yup......it too supports the front of the glock magazine

Edited October 14, 2018 by TRUBL

[jerseyglock]

Happened to me at Blue Mountain Steel Classic match couple of weeks ago. Only occurred after short stroke modification.

[TeamGE]

Hey Tim,

You bet, alive and kickin'. I am aware of your new barrel/feed ramp design and it looks to be a winner for both feeding and mag support. 

 

This is what I came up with to solve my mag support issues for both the front of the mag, and what the mag stops on when inserted into the receiver.

[TRUBL]

sweet Beven!!....... The Glock feed ramp we came up with also supports the front of the magazine and gives a little pre ramp as well. It was purely by mistake one day I was looking at the design of the feed ramp on an upper with a barrel attached.....and said......why the hell can't we do that on the barrel in this day and age of CNC wizardry!! And booom!!! the Extreme Feed barrels were born

[mveto]

1 hour ago, TRUBL said:

sweet Beven!!....... The Glock feed ramp we came up with also supports the front of the magazine and gives a little pre ramp as well. It was purely by mistake one day I was looking at the design of the feed ramp on an upper with a barrel attached.....and said......why the hell can't we do that on the barrel in this day and age of CNC wizardry!! And booom!!! the Extreme Feed barrels were born

That was the reason I put the feed ramp into my PCC, I never had any feed issues with my barrel but could see that the front of the mag was not supported at all, then I read a thread somewhere that mentioned the feed ramp and that it also supported the front of the mag. Installed it and have not had any issues with it and no blown out mags.