Bad Mag Body?

[Sin-ster]

I ran into a problem this weekend with one magazine for my Production rig, and it's got me pretty baffled. Out of no where, when loaded to max (17) capacity (and often anything past 6), the nose of a round will get stuck within the body and bind up the follower, while those on top (typically 2) will float around. Interestingly, the gun fed everything fine when it first happened, but I pulled the mag when hand cycling showed the problem to be pretty pronounced. 5 other mags don't suffer from it.

Some info:

I load Uber long-- 1.160, with nothing ever measured higher than 1.161. I'm fairly certain up to 1.165 works in these mags, from past tests. At 1.170, I get a 30% chance of these problems happening in any mag (tested with dummies).

The mag-in-question is between 5k-10k deep in use.

Using Wolff extra power springs.

Bullets are MG 124 JHPs.

(Visibly) shorter rounds don't cause the problem, obviously. (They were also RN, and less prone to a snag I'd imagine-- but never felt a drag at all.)

Bullets do not come out of the working mags with visible deformation or "wear" on the nose.

Thoughts:

Maybe some drag on the nose of the bullets has built up some deposits in the body? Unfortunately, I can't see or feel where! (And no visible burrs, bends or obstructions.)

I scrubbed the mag out pretty darn well and saw no improvements.

I swapped to a fresh spring (these have less than 1.5k on them) and had the same problem.

I swapped the guts from a working mag into this body and had the same problem; the guts from the defunct mag worked fine in the "good" body.

The follower is in pristine condition, visually.

Since it's this one mag, my obvious thought is to simply replace it and keep the "bad" one aside for other applications. Frankly, I don't even know if it'll have this problem in a cycling gun-- but I'm obviously not willing to take the chance when it matters. I'm loathe to reduce the OAL as it hasn't been a problem until now, but if this is some type of wear-induced failure... it may be the best option, before the others start to crap out.

Anyone run into this in the past? What should I look for as an indication of the cause? How might I go about correcting it?

[LPatterson]

My first thought is that you have been very very lucky with the other 5 mags. How about some more information on the mags, Gen 3, SF, Gen 4, follower #. The design of the Montana Gold 124gr HP leaves some pretty sharp edges on the nose of the bullet so my SWAG is that under recoil the nose of the bullet is catching the front of the magazine. Why is it that you don't want to back off a few thounds to insure 100% reliability. Personally I run them at 1.135 but that length came after getting a KKM barrel and trying to shoot 130gr BBI and not wanting to keep change the OAL every time I changed bullets.

[Duane Thomas]

I load Uber long-- 1.160

There's your problem right there. What advantage do you think you're getting from such a long OAL? In any event, shorten it up to standard length and in overwhelming probability your problem will go away.

[Sin-ster]

They are Gen 3 mags, and sadly I don't have them in front of me to pull the follower number. I am 90% sure it's a 6 or a 9, depending on how you look at 'em. Full metal lining, square behind the lips-- definitely not old ones.

I've been told by several shooters to load as long as possible. (Brian says it in his video-- no kidding!) Improved feeding definitely comes to mind, and I've seen it personally solve issues that even feed ramp work could not. Reducing the lead typically serves to improve accuracy, at least in rifles-- and these things have been accurate from day 1. (Anecdotal perhaps, but factual nonetheless.) There's also the leeway for a random blip out of the powder measure-- longer means less pressure, on the off chance one catches an extra tenth or two. I'd also imagine it would alleviate pressure in general, on the off chance a bad piece of brass slips through. Logically speaking, it should also account for more consistent OAL's as there's not so much "brass on brass" in the seating process. (My ES on OAL is .003, with the SD somewhere in the .001 department.)

With over 10k through these 6 mags and only now running into a problem with 1 (body) in particular... Calling it "lucky" to have avoided an issue until now would be inaccurate, in the extreme. If anything, this one body just screwed me over!

I'm sure if I dropped it to 1.150-1.155, it'd work just fine. This new batch of bullets would probably not be seated any deeper than my originals, as the nose profile changed and I actually cranked them out a little bit longer to get to 1.160.

Light bulb as I typed that-- my guess would be the slightly flatter and sharper edges are part of the problem. I'll have to check on that.

Nonetheless, the fact remains-- through at least 3k of these new rounds, which this particular mag saw more than it's fair share of (call it 750), the thing ran perfectly. And out of the blue, inexplicably, it took a crap. I'd rather not change a thing and figure out how/why, and either replace/repair the body... or make an informed decision to alter the length of the loads.

Because paranoid or not, if I drop the load .005-.010, I *will* be dropping the charge and working back up to my chosen PF. And I don't have the darned time to do it right now! (Not to mention I'll be shooting a 9 Pro by December anyway, using this as a back up.)

[Sin-ster]

Oh, forgot to add...

The problem arises most notably through hand "shucking" the rounds out of the mag. When I first felt it happen (in the gun), the next shot set things straight. I wish I had the time this week to get out and shoot it to see if it'll actually work acting so funky...

TBH, they all act a bit sluggish from time to time when emptying them by hand, but never stick. This is the first time that's happened.

[Duane Thomas]

The 9mm has a very thick web, it's a hugely strong little casing which was designed to survive pressures well beyond what we typically run here in the U.S., both in factory ammo and handloads. A few extra tenths isn't going to make a difference. If your magazines - at least one of them - will not feed your long loads, but will feed them at standard length - and they will - then reduce your loads' OAL, call it good, and focus on firing your perfectly functional handgun. My $0.02.

[Duane Thomas]

Having said all that, I did recently get in a mag with one of my article sample guns, a 17-round 9mm, that, even at the length I was loading my ammo - 1.150" - would also perform the exact same trick you describe. And that was with solids, not hollowpoints so it was obviously the length, not having a hollowpoint that was the issue. It may well be possible that certain recent production Glock mags are shorter front-to-rear of the interior steel tube than they should be. However, I'd still look at shortening your OAL as the obvious first response. There's really no reason not to.

[Braxton1]

The "Load as long as possible" advice is easily quantified as "Load as long as possible as long as the danged things work".

I haven't found any reason to go really long (over 1.135) in a Glock, especially with Production Division powder-puff loads. If I were loading 9Major in an Open gun, I'd consider going a little longer, but not at the expense of reliability.

[Sin-ster]

Seems like sound advice, especially if my perceived benefits are unfounded.

Still, the curious monkey in me wants (has?) to know why this started happening out of thin air, to a mag that had previously run at that length without a problem.

A catch-all fix may be obvious, but the actual cause for the change remains elusive.

[Sin-ster]

The "Load as long as possible" advice is easily quantified as "Load as long as possible as long as the danged things work".

I haven't found any reason to go really long (over 1.135) in a Glock, especially with Production Division powder-puff loads. If I were loading 9Major in an Open gun, I'd consider going a little longer, but not at the expense of reliability.

Well now I want to load long just to be special!

Really, I just want to know what caused the sudden change. The long OAL could easily be the cause, when coupled with the new shape of the tip-- so I'll go ahead and tune them back a smidge to avoid turning all of the mags into duds.

But I just gotta know what specifically went on in there! (Yes, I'm insane like that.)

I should have time tomorrow to pop it open again and really get a good look inside. If I find anything, I'll be sure to re-post. I know my curiosity has rubbed off by now, right?

Anyone? Bueller?

Edited November 8, 2011 by Sin-ster

[Duane Thomas]

The "Load as long as possible" advice is easily quantified as "Load as long as possible as long as the danged things work".

Excellent point.

[Duane Thomas]

If it helps, the Speed reloading manual lists an OAL of 1.120" for a 124-grain HP, so you are definitely way over spec.

[Duane Thomas]

I should have time tomorrow to pop it open again and really get a good look inside. If I find anything, I'll be sure to re-post. I know my curiosity has rubbed off by now, right?

Anyone? Bueller?

It's hard to be curious when the solution to the problem is so obvious.

For what it's worth, I had the exact same problem you did. Yeah, I wondered what had suddenly gone wrong when the gun had worked with that ammo, with that mag, for many rounds. But the truth is it doesn't really matter. Solve the problem and move on. I shortened the OAL and returned that mag to Glock when I returned the article sample gun with which it had come. (Yes, I was using those mags in my gun, as well.) Now my gun works perfectly again. Really, that's all I care about.

[Duane Thomas]

Also I wouldn't bother dropping the load then building back up, given (1) the strength of the 9mm Parabellum case, (2) the wimpy pressures at which we run our "standard pressure" 9mm ammo in the U.S., both factory and handloads. Really, compared to what that casing was designed to handle we should call our stuff "minus-P" 9mm. Just keep the powder charge the same, crank the seating die down until you're getting 1.120" and start turning out ammo. BTW, and I say this as someone who has done this in the past, I'd be amazed if you see much if any difference over the chrono.

[Sin-ster]

Also I wouldn't bother dropping the load then building back up, given (1) the strength of the 9mm Parabellum case, (2) the wimpy pressures at which we run our "standard pressure" 9mm ammo in the U.S., both factory and handloads. Really, compared to what that casing was designed to handle we should call our stuff "minus-P" 9mm. Just keep the powder charge the same, crank the seating die down until you're getting 1.120" and start turning out ammo. BTW, and I say this as someone who has done this in the past, I'd be amazed if you see much if any difference over the chrono.

My press has been bumped and moved a round a bit recently, plus I'm about to start working up a load for a new gun anyway-- I'll drop it a tenth or two just for giggles.

I doubt I'll go that short on the OAL, but I'm definitely going to bring it down significantly. You're right about the cause not mattering, as I'm losing nothing but shortening up and gaining the knowledge that it won't happen again.

I do have to say, though-- you'll never learn anything if you're not endlessly curious. I will be figuring out what happened-- it just might take me longer!

Thanks for all the good advice!

Edited November 8, 2011 by Sin-ster

[Duane Thomas]

Yer welcome.

[Sin-ster]

Well, I snuck off to the range today as I won't be able to do my usual practice at the end of the week. (I have to miss the plate match on Friday as well, and Steel on Saturday. Argh! I better shoot well on Sunday or I'll be pissed!)

I jammed that puppy full to the brim, with 10, with 11, with arbitrary numbers like 7 and 14 and it never choked once. Probably 300 rounds through it in this fashion, and narry a hiccup.

I began with 17 in the mag, which typically makes it the most pronounced when "finger shucking" the rounds into a bag/box. Slowfire, paying specific attention to grip and follow through, I broke a shot and paused, then shook the gun and removed the mag. Nada. Repeated 3 times and could feel instantly (as I did last weekend) that there was a stuck round. Pulled the mag gently and indeed, a few floaters on top and a jam somewhere down in the body. Replaced the mag (gingerly), got a perfect sight picture and snapped off a 6 round Bill Drill. Everything fed fine.

I proceeded to do everything I could to make the gun choke and it simply refused to fold. I found that under recoil, the nose dive is actually pretty rare (as you can feel it happening in the gun), and it never results in an FTF. At the same time, it's distracting and may indeed worsen over time. Still going to drop the OAL, in other words-- but I found this to be pretty interesting/encouraging.

I should have some time tonight to pull the sucker apart and really see if there's any kind of bur or buildup in the body.

[Flexmoney]

Anyone run into this in the past? What should I look for as an indication of the cause? How might I go about correcting it?

Yes.

Bullet profile and OAL. Pretty obvious and not uncommon. That puts your loads on the "margin". Get a mag our of shape a bit (or any number of other things) and...fail.

One of the main reasons to have a Glock is that it runs so well.

Well now I want to load long just to be special!

Keep loading them waaay out there and you can be special...in that you've caused a Glock to fail due to your loads.

Seriously, loading to 1.135-1.140 is still "long"....per the book specs.

[LPatterson]

To put OAL in perspective but using a different caliber Lyman list the 40 S&W with an OAL of 1.135. Winchester is loading their Ranger 155gr JHP [RA40155HP] at 1.120 while Federal loads a 155gr JHP [XM40HB] to 1.127. So maybe in other sports longer is better.

[Sin-ster]

The mag-in-question is magically... fixed again.

I can't get a round to nose dive in it to save my life, even hand shucking the thing. Whatever build up/burr I had created must have smoothed out during my 300 round test session last week. Still, I pulled it out of the rotation for matches and will be dropping the OAL anyway.

10k+ of this bullet profile, at this length, through this gun (and mags) and never had a single (actual) problem. Even jamming up, the mag continued to feed the gun as fast as I could pull the trigger-- when I first noticed the problem, and in testing. So nyah, nyah! But you're right about the "margin", Flex. This proves that I'm right on it. (As that was my goal, though-- I'd call it a success, and not a failure. )

I knew I was running Uber-long, but I learned that the benefits I was after were just imagined. Especially in a Glock, that can feed just about anything. With my M&P 9 Pro returning from trigger work in the next couple of days, and taking over as the primary Production piece, I'll just have to run a load that'll work both of them properly. Looks like 1.130-1.135 is going to be it, based on the measurements I pulled from the M&P barrel before I sent it out.

.03 ought to be enough to keep this from happening to the Glock mags again!

Edited November 14, 2011 by Sin-ster

[BoyGlock]

I was searching for a probable cause of my jam due to a mag in my glock 17 open 9maj that cost me the match last weekend when I read this thread. Quite similar but no nose dive. The gun completely did not feed a rnd in the chamber. It was my 1st stage of the match, got the gun running for 3-4 rnds, then CLICK! thought it was a misfire or a case failed to extract, retracted the slide, was surprised nothing extracted, released the slide, proceeded to shoot, after 3-4 rnds, another CLICK! same thing happened. Finished the stage @ 15sec while the best time was 9sec. Lost the match and placed 2nd at 95.5% from the top. Its a local match so no top dogs around.

That mag and the rest of my mags ran perfectly prior, for thousands of rounds w/o any prob but they are old mags I had back in my prod years. My bullet OAL was ok @ 1.135" The prob mag has arre.+4 basepad for a total of 21rnds capacity. Prior to the match, I cleaned them and applied a very thin coat of wd40 in the inner tube w/c I suspect now contributed to the jam. I used to load the mag w/ 20 rnds only but felt it could easily have more due to my cleaning and oiling, I topped it at 21 knowing its the rated max anyway. I suspect w/ the pressure combined w/ the age of the mag and the slick of the wd40, the mag body expanded a bit sideways causing 2 rounds to bind side by side on the walls of the mag thus preventing the spring to push the bullets up and delaying them a bit in time for feeding, completely missing the slide on its forward travel = empty chamber. A lesser variation of this could easily make FTF jam w/ the round caught halfway up or a nose dive.

[LPatterson]

I'd suggest the problem is two fold. First WD40 stands for Water Displacing Formula 40 it was designed to get under surface water to prevent rusting. Over time a film will develop which presents a waxy feel. If you feel something is necessary, then I would suggest something like MagSlick, Silicon, Liquid Wrench Dry Lubricant or a new one Jig-A-Loo. Secondly if you used to run 20 and all of a sudden started running 21 and had problems, I suggest that the mag springs took a set and are now binding. Get some + power springs for the extensions.

[splashdown]

Oops, never mind.

Edited December 22, 2011 by splashdown