Explosive Failure of Polymer AK Magazines… From Sitting In A Safe?

AKMag-004

Ever seen a magazine explode? Lee “The Gun Writer” Williams was greeted by the aftermath of this dramatic failure of a Bulgarian AK magazine, little more than a week ago:

 

 

AKMag 004

I had a surprise last night when I opened my safe.

The top of a loaded polymer AK mag had broken off for reasons unknown, spraying 28 loaded rounds and bits of plastic all over my safe.

The spring was sticking halfway out of the top of the mag. I found the follower behind an SKS.

To be clear, the mag was not in a rifle. It was one of several loaded mags I keep on a shelf of the safe.

The offender was a Bulgarian slab-side polymer magazine, which is usually considered one of the better mil-spec-type AK magazines

It hadn’t been loaded for that long, maybe a couple weeks. I rotate my magazines between trips to the range to give the springs a break. And as I said, it was loaded with 28 rounds, not 30.

The lesson I learned: The best AK mags are still the Combloc steel.

They’re a bit heavier, but the extra durability makes them well worth it. You can nearly play hockey with a steel AK mag without worry. They’re also easier to pull out of a chest rig than the waffle-sided variety.

AKMag 002

 

Hognose had further commentary on his blog, WeaponsMan:

What makes a mag fail like this? Lee seems to think that the guilty party is leaving the mag loaded for a length of time. We have our doubts about that and would be more inclined to suspect the cumulative effects of age and ultraviolet-ray exposure (plain ordinary sunlight, which it certainly couldn’t have gotten in his safe). But the durability of different AK mags, even different Bulgarian mags, is widely variable.

We also don’t think loading only 28 rounds buys you anything. The difference in pressure is nominal. This goes back at least as far as Vietnam and was a ritual practiced by troops (although, there it was putting 18 rounds in a 20-round magazine) who were neither trained on the rifle nor given a supply of replacement magazines. It was something they did to appease the M16 Gods

The plain ugly fact is that magazines are, by design, expendable items and you need to start thinking of them that way — they’re the toilet-paper of small arms, necessary but not especially durable or reusable. And just like toilet paper, some brands are better than others. Lee, for example, probably should dump all of his circle-10s that are the same age as the one that failed, because their clock is ticking, too. Sorry to be The Bearer of Bad News.

In the real world, private owners and armies alike are reluctant to purge their bad magazines because the mags represent a considerable cost — both the sunk cost that was spent on them and is lost for good, and (more germanely) the replacement cost for new mags. It is possible (although not necessarily economical or practical) to repair or overhaul metal, especially steel, magazines, but synthetic materials are harder to repair and rebuild.

I’m inclined to agree, but I’d add that another possibility is a materials defect. The magazine failed where the steel feed lip inserts were molded into the polymer, a manufacturing technique that requires its own science and witchery to perfect.

 

H/T, Hognose, of WeaponsMan



Nathaniel F

Nathaniel is a history enthusiast and firearms hobbyist whose primary interest lies in military small arms technological developments beginning with the smokeless powder era. In addition to contributing to The Firearm Blog, he runs 196,800 Revolutions Per Minute, a blog devoted to modern small arms design and theory. He can be reached via email at nathaniel.f@staff.thefirearmblog.com.


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  • Esh325

    I don’t think one bad polymer magazine means all polymer magazines or polymer AK magazines are bad all of sudden. The Russians have been using them for years. I don’t think they would be using them if they weren’t good.

  • Al Grrrrr

    I blame the sun. In other words, ‘global warning’.

    Thanks for ruining the planet, you bastards.

    • Jsim

      No it’s definitely Obama…

      • Old Fart

        It’s always Obama.

        • ghost

          It’s a vast right wing conspiracy. (TFB, Firearms, not politics).

          • Zebra Dun

            BUSH!

          • Rich Kerr (Papa Gato)

            Naw, plainly it’s Hillary . . .

          • Zebra Dun

            Agreed most Riki Tic! HILLARY!

    • Don Ward

      Blame it on the rain…

      • iksnilol

        Californians are blaming it on the lack of rain.

        Badumm tss

      • Cynic

        Blame it on the boogie

  • Gryzon

    Might want to also look into the process he used to paint the magazine as one of the solvents involved in paint or prep might have affected the plastic.

    • All the Raindrops

      Yep

    • n0truscotsman

      Possibly. I’ve heard of magazines being ruined because of painting. Although I’ve never heard of a single problem with krylon camo or aervoe melting or weakening plastic or polymer.

  • Sav Mike

    Steel…..is good, Da?

    • David Sharpe

      Da.

  • Scott Tuttle

    I seem to recall that loading and unloading your mags is what causes the springs to wear out, not leaving them loaded.

    • All the Raindrops

      True.

      Rotating mags is a fallacy that leads to increased wear

      • Rodford Smith

        Properly made steel springs do not take a “set” within their intended range of motion. Exceeding that range will stress them. Working them within that range will gradually fatigue them.

        Polymers are subject to plastic creep. However, modern polymers properly manufactured for their intended use should not creep within their normal load limit.

        BSCE focusing on materials testing. 🙂

        • Giolli Joker

          “Properly made steel springs do not take a “set” within their intended
          range of motion. Exceeding that range will stress them. Working them
          within that range will gradually fatigue them.”

          True, but consider that yor car has several springs commanding the valves motion, their life is measured in millions of extension/compression cycles…a properly made spring, in a non overly aggressive environment, outlasts the magazine and its owner.

          I think that here it was just a defect in the material.

          • All the Raindrops

            Definitely.

          • Nashvone

            You’re killing my buzz here. I’ve used the pressure on my mag springs as a reason to get my butt to the range.

          • Giolli Joker

            Keep on doing it, it won’t hurt. 😉

        • All the Raindrops

          Youre right… yes, I didn’t use a good description, I didn’t mean “increased wear,” just “wear.”

          Compared to a spring with no tension or a loaded mag under compression, that is. When it’s sitting there, it’s not wearing. Rotating (i.e. unloading and loading them) gives wear.

          But it is almost so insignificant as to be unworthy of discussion in this application… I was just saying it’s not really necessary to rotate mags, but whatever makes people sleep better at night is fine since the difference is minimal.

          • Rodford Smith

            Yeah. It’s like modern camera memory cards (at least the well-made ones). Each read-write-delete operation takes a bit off their lives, but they have so many cycles available that you’re unlikely to wear them out.

    • iksnilol

      I found the topic confusing. I mean, are springs that are pressed down worse? Think pistol mag left loaded for 20 years.

      I just keep half loaded and half unloaded. That way I am insured.

  • This is not uncommon. Beryl mags (the really clear ones) are the worst. You’ll be sitting up at night minding your own business and then hear a very audible cracking and then a pop.

    • BrandonAKsALot

      Surprise! It’s a cheap Polish mag. Commercial Polish stuff always has the caliber in quotes like that.

  • John

    Man, polymer is just not having a good year. First the G36, now this. What’s next?

      • iksnilol

        All-polymer mags are a stupid idea. At least have steel reinforcing.

        I wish there was a Circle 10 20 round magazine. Only lightweight 20 rounder I know of is from Tapco. I don’t really trust Tapco.

        • StBernardnot

          My Gen II Tapco 30 rounders seem do be holding up very well. Tapco also replaced all my Gen I mags at no cost. They knew they had a defective product & did the right thing by me.

          • All the Raindrops

            Gen1? Gen2? Are you referring to tapco ak mags? Waffle/slab?

          • StBernardnot

            Sorry. I should have given more detail. These are Mini-14 mags. I wouldn’t call it waffle, but it’s not slab either. I think they had Gen 1 & 2 in AR & AK, too.

          • Capn Stefano

            Mine are the latest version from late 2014

          • iksnilol

            I am just being cautious is all. I am a bit paranoid around polymer feed lips.

            Maybe cut down a Circle 10 if I want a lightweight 20 rounder? Or skeletonize the crap out of a steel 20 rounder?

          • SirOliverHumperdink

            I guess if it came down to no magazine or a tapco, I use the tapco.

        • Capn Stefano

          Tapcos are GTG, built like a tank, and the 20 rders are great kit

          • iksnilol

            Eh, they are cheap enough that I won’t mind buying a couple the next time I am buying something from the US.

  • flyingburgers

    Not a mechanical engineer but i’ll take a wild guess at the failure mechanism from the picture. The rough fracture surface is the part that failed at a high speed. The small chunk of what looks like the feed lips is smooth, which suggests a more gradual failure. I would guess that the cause is a crack caused by repeated loading on the feed lips which then propagated and ultimately caused overload.

    Looking at the intact part of the feed lips, you can see there’s scratches and gouges due to handling. I’d suggest that the owner needs to take better care or else reject magazines with feed lip damage. The design is also built too well: there should be a crack stop feature like a lip or a hole below the feed lips to localize the crack.

  • iksnilol

    Are waffle mags still okay? Since they are the only non-steel mags I use.

    • I’m not sure these are Circle 10s. I have used many, many Circle 10s that I have kept loaded – literally – for years, and never had a problem. I would recommend them.

      • iksnilol

        Doesn’t look like a Circle 10 to me. Circle 10s have the waffle pattern (except for the 5.45 version, those are slabsided). That and we don’t see the marking (isn’t it supposed to be on both sides?).

        Then again, I am no expert.

  • Will

    ANYTHING made by man can fail!

    • Cal S.

      Except AKs. They never fail. Ever.

      • Southpaw89

        Unless they’re made by Century Arms

        • Cal S.

          Is AK. It bears name AK. Failure impossible. Wicked Capitalizt propaganda.

        • SirOliverHumperdink

          You missed the sarcasm. Also Glocks never fail. (get it?)

      • Capn Stefano

        Greetings. I want to introduce you to my Waffenwerks 74 that is practically a single shot after 800 rds

        Never had a 47/574magazine failure, from Chinese and East Block steel to Tapco mags, except a Tapco drum that needed a little tweaking of the sheet steel guide piece to get to 100%

        • Cal S.

          LIEZ!!! EVIL WESTERN PIG LIEZ!!!

          AKz never fail, EVER!!!

          In case you haven’t noticed by now, I am joking. I know, like every other adult out there, that AKs can and do fail often. I’ve owned one AK and I’m currently selling it because I hate the thing. At least I’m willing to admit that AKs suck. Never again will I buy a firearm designed/built by 3rd-world country… Ever.

  • Old Fart

    Circle 10’s are the real deal. I am also willing to give Magpul’s Gen2 AK mag a go, but they better perform this time.

  • Jeff Smith

    I had something similar happen with a Mini 14 magazine a while back. I got the rifle back in the 1990s and bought a pre-ban 35 round magazine from the brand Eagle. Several years ago I noticed a crack in the back spine of the magazine near the feed lip. After loading it, the feed lip gave just enough to allow me to play a game of “35 pick up.” It didn’t break all the way, but it did launch all the ammo out.

    • Rodford Smith

      The polymers used in magazines (and most other things, actually) can deteriorate from exposure to common environmental chemicals. Volatile fumes from fuels and solvents, for example. Ozone is a major contributor to such failure. Exposure to the UV in sunlight can also have a harmful effect.

      The effect is slow and can take decades given the typical exposure in, say, a basement where gasoline is stored or cleaning agents with solvents used. Even the chlorine fumes released by bleach from the laundry can slowly turn many plastics brittle.

      • Sulaco

        So how bout all them polymer receivers in use for years with similar exposure? Picking a pistol totally at random…….Glocks?

  • Rob

    This shows the strength of the AK spring, it was strong enough to break its own “plastic”…which is kind of cool. The polymer most likely failed because of multiple stresses over time, I’d guess those stresses were from “tactical” reloads, slapping the new mag into the mag release/old mag, and the old mag hitting the ground. I guess there could be other causes, bad material, or molding? Who knows, but interesting none the less.

    • nadnerbus

      Interesting thought with the tac reloads.

      It does seem like there is a thing with AK guys, where they expect everything AK related to be built like a tank and able to take extreme abuse. Tim from MAC took the new Pmag, inserted in an AK, and bashed them on a table until it snapped. On that basis he felt they should be improved.

      Not saying that there are not stronger methods to make AK mags that make them nearly indestructible, but at some point I think you can get too demanding on the level of abuse a magazine can take. They are essentially semi disposable accessories to a firearm. They just need to feed well, be reliable, and strong enough for most of the abuses they are likely to see.

  • Lance

    Keep saying AK steel mags are the best. That’s why the Commies kept using them when polymer mags where becoming the norm.

    • Esh325

      When the AK-74 came out, the Russians didn’t even make steel magazines for them, they only used plastic.

      • Weren’t the first AK-74 mags bakelite? I know it’s technically an early type of plastic but IIRC it’s rather different compared to modern plastics and polymers.

  • Darkpr0

    Polymer is a neat material. It has a ridiculously good strength to weight ratio, it has a wide variety of applications, it is easily molded into shapes not possible any other way…. Good stuff. On the inside these properties happen because polymer molecules are like spaghetti. Extremely long, thing chains all in a giant tangly mess with occasional meatballs of well-organized, crystalline area. It’s very unlike many other things we’re familiar with, but it also presents some neat behaviours. Stuff like Crazing (bend plastic, it turns white), really strange stress-strain diagrams… This is definitely a weird behaviour, though.

    Just looking at what we have here, I see the steel reinforcement bars for the feed lips, and the crack lines at the very base of them along the edge. I also note the the jagged crack is generally perpendicular to the force you would expect from the mag spring. That type of crack suggests a sudden, brittle failure which is not typical for a thermoplastic polymer at yield stress… You’d expect signs of stretching and pulling if it was overstressed. This looks like a fatigue failure to me… Fatigue only usually happens when a cyclic load is applied, not one that is constant. But I do know that polymer under constant stress will slowly stretch (called “creep”), and has some other strange fatigue properties so you never know. The constant stress of the spring + temperature fluctuations of the room could have done this if it’s left loaded for a long time, as that makes the ;pad cycle from thermal expansion/contraction of the mag itself. That’d be my guess.

    On another note, I’ve heard the 18 rounds in a 20 AR mag story from a Vietnam vet in person. He said that when the mags got wet or muddy they would malfunction if they were fully loaded but run fine if underloaded. I can’t confirm that, nor did he say he ever personally had a malfunction, but that was the story I heard.

    • Ben

      Creep in polymer materials typically only occurs at elevated temperatures or stress levels very close to the yield strength. I concur that this failure looks to be caused by fatigue. A gunsafe should remain a fairly consistent temperature though, preventing significant thermal expansion or contraction.

      Perhaps the fatigue stress was caused by rotating the mags. Leaving mags loaded doesn’t actually do harm to the springs. I have a pair of 15 round M1 Carbine magazines that my uncle brought back from Korea. They are currently in my gunsafe, fully loaded with ammo that is headstamped as 1953 production, and they have been sitting around loaded that way for the last 62 years. If you unload them, the springs still have full tension.

      Maybe with polymer magazines like this, it is actually better for them to store them loaded or unloaded all the time. Granted, most of the loading/unloading stress cycles comes from actually firing them. But if their failure criteria is based on fatigue, then minimizing the number of stress cycles that they are subject to could delay failure. So stop rotating the ammo out of your mags.

      • Darkpr0

        Creep behaviour depends on the exact polymer, as well as if there are any other additives such as in composites like CFRP which can take the load. The purpose of pointing out that polymers can do this is to illustrate that their behaviour over the long term is not like metals. The nice thing about M1 carbine mags (specifically USGI) is that they are made out of steel, a material that has very good fatigue properties, including a minimum strength that they will never* (arguable) fatigue down past. Ditto the spring. Because steel is quite strong, these mags are also quite thin which is nice because thinner materials resist crack propagation better than thick pieces. Aluminum doesn’t have the min fatigue strength steel does, and the mags are made of thicker stuff so as to be stiff and strong enough, and so I’d wager if you tested a new repro mag it wouldn’t hold up nearly as well. Continuing that scale, it’s my personal belief (though unprovable with the sources currently inside my brain) that polymer would have poorer fatigue properties than aluminum, but they have the advantage of being cheap so you can replace ’em as need be.

        I’m not sure I’d jump on the leave-ammo-in-forever train just yet, as I’ve seen some people leave their nice, greased up mags with ammo forever, fire one round, and then fail to load a second one in because the follower is gunked up with really old lube. Inspect your mags, people. Crack propagation doesn’t happen overnight. Give your mags the same loving attention you give the rest of the machine, they’re what make your single-shot rifle a semi-auto.

        • BryanS

          Just to chime in, this is the most intelligent conversation I have ever seen on a website regarding polymer mags.

          (“Space age” material… AK 1960’s tech. Ha!)

          • Darkpr0

            OMG POLYMER MAGS LOL TERRIBLE. Does that look like a more familiar internet discussion? 😀

            Seriously though polymer is really great stuff. Designers are still learning where it can and can’t be used. I think if ceramics and cermets ever make their way into the industry we’ll be going through the same learning experience, with much the same improvement in capability by the end of it.

  • All the Raindrops

    This article makes me like my tapco slab sides even more, no tricky metal embedding process 😉

  • David Sharpe

    The only time I have ever had a mag fail it was one of those 10 round butler creek 10/22 mags, I cleaned it with some Bio-Circle L gun cleaner that my range has. The next time Used it the seem failed. I put it back together and a little super clue and a couple rubber bands, good as new!

  • Machinegunnertim

    When talking about “polymers” you are talking about a broad range of many
    hundreds of possible materials, many having completely different properties. If
    I talked about metals you might ask, is it steel, aluminum, and titanium? If so
    what type of each?

    This looks to be a defective magazine. Either the material was
    not the correct type or blend, or the temperature or something in the molding
    process of this magazine. All of the Lancer magazine are polymer with steel feed lips molded in and I’ve never heard of this happening to them.

  • Sergey

    Please stop being so sensationalist.

    The magazine came apart and failed while not loaded, but you make it sound like a round detonated inside of it by saying “explosive”.

    • Don

      What story did you read? He clearly stated that the magazine was loaded with rounds and that when he opened up the safe he found parts scattered everywhere, hence “exploded” magazine…

      • Sergey

        See how misleading that was? I’m talking about being loaded into the rifle.

        • Well, I don’t know about you, but if I had a loaded magazine burst apart like that in my hands, I would say that it “exploded”.

          But just to convince you further, I’ll break out the Merriam-Webster definition of “explosive”:

          1
          a : relating to, characterized by, or operated by explosion b : resulting from or as if from an explosion
          2
          a : tending to explode b : likely to erupt in or produce hostile reaction or violence

  • patrickiv

    Looks more like a manufacturing defect. How many millions of these were made?

  • caleb

    I would like to clarify, since the author does not. That is NOT a Bulgarian Circle Ten mag. That is a COMMERCIAL mag. Circle Ten mags in x39 are waffle pattern, and NO Circle Ten mag I have ever seen is marked with the caliber like that.

    • M

      Yep, there’s actually quite a story and controversy behind these magazines.

      “Metal reinforced feed lips and locking tabs” for AK magazines have become analogous to “Properly staked” bolt carriers for AR-15s. Both have become buzzwords that many look for and [erroneously] equate with quality.

      Basically, the people that made these magazines were taking advantage of that fact, and marketed it as a “surplus” “metal reinforced” magazine.

  • Tom – UK

    There really isn’t much point loading 28 rounds in a 30 round magazine. The manufacturers sat down and designed a product to speciically take 30 rounds so put 30 in it.

    • Machinegunnertim

      I’ve been telling people the same thing for years! If your mag can’t work at full capacity it is defective and should be replaiced with one that can.

      • CZFan

        I dont know about the whole downloading 2 round origin, Ive never heard the Vietnam Connection Before and I know quite a few Vietnam War Combat vets.
        I do know that it is much easier (and more reliable) to stick a magazine with 28 rounds in a gun with a closed bolt (for a tactical reload) than trying to do it with one with 30 rds. Ive seen alot of experienced shooters and specifically new ones end up with a “malfunction” after a “tactical reload” because the magazine is difficult to seat all the way in one movement.

        It usually takes someone inserting the mag and then giving it a firm push while letting the guns weight help to lock a mag fully loaded onto a closed bolt.

        But you are right if your magazine has issues consistently I would toss it. Thats what I do. But some people hate to throw mags away especially when a PMAG was selling for $45 each at one point…

        • Machinegunnertim

          I get what you are saying too. You are mostly referring to the old aluminum military spec AR mags that are very tight on the rounds with all 30. The Pmag and other current designs put a lot less pressure on all 30 rounds and don’t have this problem. Yet people download them to 28 still, and many don’t accurately understand why they are doing it.

          • CZFan

            For sure Pmags are much easier to insert fully loaded, and I forgot to mention that Use PMAG’s almost exclusively and I just load 30rds in them and use the dustcover that I have for all of my PMAG’s for storage, that protects the feed lips and as an unintentional bonus it seems to make them even easier to insert fully loaded after they have been sitting for a while.

        • Phillip Cooper

          This is why you are supposed to slap the magazine into the weapon, hard. If it can’t take that, find a mag that can.

          • CZFan

            you are supposed to insert the magazine with one deliberate movement, sitting there and trying to slap it to get it to lock is a waste of time, not only that if you are having a problem getting it to lock because its a full mag and the bolt is closed slapping it usually wont get it to lock no matter how hard or how many times you hit it.

            The only ways I have found that work to get around that problem is to download by two, then without fail the magazine will insert smoothly and quickly on a closed bolt, or while you reload after the mag is inserted fully but not locked you push up really hard and let the gun “fall” down into the magazine at the same time, using the guns weight and a firm push to compress that last little bit of spring.

            Or with PMAGS store them with the dust cover on fully loaded and after a while they are alot easier to insert on a closed bolt.

            I prefer the last option, but even then every once in a while the thing just does not want to lock and you are back to pushing really hard and using the guns weight to help.

          • Phillip Cooper

            Actually I wasn’t telling you what is “supposed” to be done, but what we WERE trained to do as an 11B Soldier (many, many years ago).

        • Bowserb

          I’m pretty sure Vietnam and the M-16 were the origin of the -2 mag load “rule”. With one-year service in Vietnam, lots of wisdom was passed on from one generation to the next. Also when it is hot and you are sweating, those last two rounds can be tricky to load. That may be where it started!

          Remember how it was well known that at least parts of the M-16 were really made by Mattel? Rumors and legends are what the infantry lives by. At one point, we “knew” that the whole 1st Division was going to be shipped out from Vietnam to Korea, after the Pueblo boarding and capture by North Korea.

          I’ve never been able to shake the -2 mag rule with the AR, as much as I’ve tried, so I have a bunch of steel 18-round mags, some polymer 28-round mags, and even a couple 38-round mags clamped together.

  • 74man

    Looks like you found out what many Kalash purists already know. Commercial mags are trash. If you want the best its Circle 10 or Surplus Steel. No Korean steelies, or poly Polish/Bulg commercial mags.

  • Jeff

    That is *NOT* a Circle-10 military grade magazine. Those are the cheap commercial mags that are marked “Made in Bulgaria” and are not metal lined. They come in slab-slide, translucent, and with bullet pictograms along the sides of the magazine. Legit Circle-10 magazines are waffle pattern (7.62 & 5.56) or slab-slided (5.45 only), marked with the ((10)) logo, and are steel reinforced along the locking lugs, feed lips, and front face of the magazine.

  • Tom Currie

    A piece of plastic that cracks and fails is NOT “explosive”!

  • Sulaco

    “We also don’t think loading only 28 rounds buys you anything. The difference in pressure is nominal.” Actually not sure that’s true. Remember reading a study done (can’t remember where…) that found that spring pressure increases at a higher percentage as the number of rounds increases. Furinstance ten rounds my cause X pressure on the spring but 20 rounds will double or triple that and leaving 5 out of the mag significantly reduces spring compresson. Or so it said…

    • iksnilol

      I know people who loaded 20 rounds in 30 rounders to help against the mag wearing out. Then again it was a war and you couldn’t readily buy magazines.

  • Jeff Heeszel

    Looks like there’s glue-ooze on that one piece. Why use plastic when steel works just fine?

  • hkguns

    I guess this shows, definitively, leaving your magazines loaded can harm them.

    • All the Raindrops

      No, it doesn’t show anything definitively.

      Better that the mag committed suicide on its’ own than while it was needed.

  • claymore

    The ARMY itself recommended only 18 rounds in the early 20 round M-16 mags. Google

    “Cathy’s Tip of the Week” for the advice.

  • dindu nuffin

    was this the new manufacture mag or soviet era? the rumor is that the old soviet era mags are better quality.

    • All the Raindrops

      this is a newer

  • Brian M

    Looks like a polymer goof. I’ve never heart of any kind of mag commiting suicide like this.

  • Paul White

    Like hell I’m going to treat my magazines like toilet paper. Not unless I can buy a 48 back for 20 bucks on Amazon. I don’t expect them to hold up to as much abuse as an actual gun but they certainly shouldn’t just fall apart or fail under normal conditions and a couple of years of use.

  • Micheal Tarr

    A couple thoughts: first, it’s completely possible to refurbish magazines, even reinforce them. i don’t see why you couldn’t insert small pieces metal into the lips of a polymer magazine. I can do it at home using a dremmel and some epoxy. Magazines are a simple device. You can print those suckers nowadays in a 3d printer just fine. If one were to make the 3d printed version with a cutout for some metal inserts, i wouldn’t even be concerned about them failing. And if they did, you can just print a new one and transfer the spring.

  • Liam Dillon

    These are commercial grade mags with no steel reinforcement at the feed lips. Genuine military mags would have steel locking lugs, feed lips reinforced, and all steel in the spine i believe.

  • Bruce Silva

    I’ve had cleaning solvents and lubes have a chemical reaction to modern plastics over time. Even brass and solvents will create problems….
    The problem appears at the upper end the magazine where bore cleaners will accumulate and judging by the appearance of the damage it looks as though the magazine plastic has crystallized….lodgic tells that anything that will remove copper and lead deposits will have an adverse effect on plastic.

  • Tony V

    I came across this article at C Products Defense

    Metal vs. Polymer Magazines
    C Products Defense has been winning OEM contracts across the globe because of the performance of our metal magazines (stainless steel and aluminum). Polymer magazines, which have been banned by the United States military since May of 2012, are hygroscopic in nature, in other words, they have a strong affinity to attract moisture and will absorb moisture onto their molecular structure when exposed to the ambient air. This moisture, within the polymer, reacts constantly with the surrounding environment.

    At the molecular level, water vapor, surrounding a hygroscopic polymer element is absorbed into the polymer. As the vapor pressure within the polymer increases to equal the vapor pressure surrounding the polymer, equilibrium occurs. This is referred to as, polymer moisture equilibrium or PME. When an environment of hot, dry air surrounds a wet hygroscopic polymer element, the vapor pressure surrounding the polymer is lower than the vapor pressure within the polymer. Consequently, the moisture within the polymer begins to migrate toward the area of low vapor pressure outside the polymer. Expose the polymer to a hot, dry atmosphere for a sufficient period of time, the polymer eventually reaches moisture equilibrium with the surrounding dry conditions. In other words, the polymer becomes dry and deformation will occur, changing its shape from its original design.

    The opposite is also true,when the moisture within the polymer is cooled sufficiently, say below the freezing point, the moisture will actually freeze and the polymer will crack as happened and reported by the Chicago Swat Team this past winter. Officer Frank Gaber, who is the Armorer and Instructor for the Chicago Swat, reported that this past winter they had multiple reports of a polymer mag shattering (and bullets scattering) when they were dropped on a hard surface. This was actually due to the moisture within the polymer and when that moisture froze it caused the magazines to shatter.”

    Consequently, the only magazines that the Chicago SWAT Team will use are C Products Defense magazines.

    Finally, we all know how moisture attracts dirt and dust and gives it a place to collect. In a firearm, dust and dirt gives way to a corrosive cocktail which will lead to excess wear and eventually early failure of the firearm.

    Aluminum or stainless steel do not have an affinity for moisture and any moisture (through condensation or immersion) remains on the surface and is easily removed by evaporation or just wiping it down. No moisture is absorbed into the metal. And our proprietary coating which bonds at the molecular level and will never wear off, decreases the coefficient of friction and increases the lubricity which means that even if you are using the dirtiest ammunition on the planet, our magazines will not jam because there is no dirt and dust accumulation or attraction.

    C Products Defense has been winning OEM contracts across the globe because of the performance of our metal magazines (stainless steel and aluminum). Polymer magazines, which have been banned by the United States military since May of 2012, are hygroscopic in nature, in other words, they have a strong affinity to attract moisture and will absorb moisture onto their molecular structure when exposed to the ambient air. This moisture, within the polymer, reacts constantly with the surrounding environment.

    At the molecular level, water vapor, surrounding a hygroscopic polymer element is absorbed into the polymer. As the vapor pressure within the polymer increases to equal the vapor pressure surrounding the polymer, equilibrium occurs. This is referred to as, polymer moisture equilibrium or PME. When an environment of hot, dry air surrounds a wet hygroscopic polymer element, the vapor pressure surrounding the polymer is lower than the vapor pressure within the polymer. Consequently, the moisture within the polymer begins to migrate toward the area of low vapor pressure outside the polymer. Expose the polymer to a hot, dry atmosphere for a sufficient period of time, the polymer eventually reaches moisture equilibrium with the surrounding dry conditions. In other words, the polymer becomes dry and deformation will occur, changing its shape from its original design.

    The opposite is also true,when the moisture within the polymer is cooled sufficiently, say below the freezing point, the moisture will actually freeze and the polymer will crack as happened and reported by the Chicago Swat Team this past winter. Officer Frank Gaber, who is the Armorer and Instructor for the Chicago Swat, reported that this past winter they had multiple reports of a polymer mag shattering (and bullets scattering) when they were dropped on a hard surface. This was actually due to the moisture within the polymer and when that moisture froze it caused the magazines to shatter.”

    Consequently, the only magazines that the Chicago SWAT Team will use are C Products Defense magazines.

    Finally, we all know how moisture attracts dirt and dust and gives it a place to collect. In a firearm, dust and dirt gives way to a corrosive cocktail which will lead to excess wear and eventually early failure of the firearm.

    Aluminum or stainless steel do not have an affinity for moisture and any moisture (through condensation or immersion) remains on the surface and is easily removed by evaporation or just wiping it down. No moisture is absorbed into the metal. And our proprietary coating which bonds at the molecular level and will never wear off, decreases the coefficient of friction and increases the lubricity which means that even if you are using the dirtiest ammunition on the planet, our magazines will not jam because there is no dirt and dust accumulation or attraction.

  • Phillip Cooper

    If you look at the broken bit, it’s clearly flowed at some point. That would indicate heat exposure. There’s your problem…

    Regarding “rotating the mags to give the springs a rest”. This is a wasted effort, and a wive’s tale. Look up the physics behind soil springs- they’re designed to take a constant load without issue.

  • Vitsaus

    Weird, figured it would be a magpul spontaneously exploding in the safe.

  • Zebra Dun

    The old M-16 we were told not to load more than 18 rds to prevent a jam and lo and behold if you loaded up with a full 20 the thing would jam, Live ammo or blanks those old 20 rd mags had some problems.

  • Big Brother

    hmmm I disagree with mags being disposable to a degree when you spend $20.00 and up on a mag it is not disposable. 8 dollars yeah maybe

  • Grindstone50k

    Other than complete failure, there is no reason to ditch old mags. Use them for casual range shooting. Leave the pristine “combat” mags at home.

  • jerrythegeek

    In regards to the “myth” that loading 18 rounds into 20 round m16 magazines during the Vietnam war was a viable choice … uh huh, we did it. And for good reason.

    A fully loaded 20-round magazine was unreliable when reloading; the spring tension made it difficult to consistently reload during ‘stressful situations’. (You know, like people are trying to kill you and you’re tring to kill them back?)

    We (members of my infantry platoon) found, in experiments on the First Inf. Division shooting range, that it was much easier to reload short-loaded magazines. Better 18 rounds you could be sure of, than 20 rounds that may or may not seat.

  • Scott Gammons

    I would say this is a manufacturing defect. No way polymer breaks like glass unless it was frozen to about 100 below zero and smashed with a hammer. Even then I’m not sure about that kind of failure happening. I think the cracks were formed via crazing of some sort and the mag died a ‘natural’ death due to this flaw.

    I have had bulgy mags loaded for years at a time and they function flawlessly. That mag looks like cheap garbage if you ask me.

  • Adam

    When i was a tooly in a Injection molding shop, From experience, I could say, the molding temp might of being too high, water flow for cooling the dies might have been too low and it cooked the plastic, making it brittle or the plastic blend was wrong..