Magpul (Finally) Explains What Killed the Polymer Coffin Magazine

A reliable “coffin” style magazine is perhaps the holy grain of high-capacity enthusiasts. While drums are certainly a proven technology, they often suffer from large volume relative to the ammunition contained inside which then causes other issues like uncomfortable shooting positions, inability to get into full prone, etc. Still, the higher capacity brings them out again and again.

Its a not so quiet secret that Magpul had previously worked on a polymer coffin magazine and through their work even patented an architecture for a quad-stack magazine with the internet and enthusiasts set ablaze when the patent went public in 2010. Unfortunately for us enthusiasts, the mythical Magpul quad stack was never to be and only Surefire’s offering is available to this day.

Magpul has always been tight-lipped on the magazine and points to the D60 as meeting the majority of the requirements by being high-capacity with minimal bulk. True, it is, but its not a coffin mag which at least did exist in Magpul’s R&D labs. Announced on March 27th on Facebook, Magpul finally opened up on why the magazine did not exist:

Quad Mag Prototype, 60-Round Capacity 2009
Shortly after the introduction of the original PMAG, Magpul began working on increased capacity solutions. The “Quad” or “Coffin” mag concept never delivered the reliability in rough handling and adverse conditions that we require from our magazine products, and so the design never made it into production. Lessons learned during this program eventually fed into the D-60 program.#MAGPUL#PMAG10YEARS#MAGMONDAY#PMAG

Nuts. LIke many commenters on their facebook page, I would take the coffin magazine over the D60 (which to Magpul’s credit, does work very well).

Nathan S

One of TFB’s resident Jarheads, Nathan now works within the firearms industry. A consecutive Marine rifle and pistol expert, he enjoys local 3-gun, NFA, gunsmithing, MSR’s, & high-speed gear. Nathan has traveled to over 30 countries working with US DoD & foreign MoDs.

The above post is my opinion and does not reflect the views of any company or organization.


  • Giolli Joker

    “the holy grain”

    • noob

      Gluten-free firepower

      • Major Tom

        100% daily value of fiberpower.

        • noob

          Bring me my brown pants.

      • GaryOlson

        Genetically Modified Ogive. Friction resistant with a sweeter finish and no aftertaste.

    • SP mclaughlin

      Don’t you know text-to-speech is an acceptable way to writ articles now?

    • No one

      Well, it does let you unleash a holy amount of grains of lead and copper without reloading.

    • mazkact

      New Ezekiel bread choice.

  • USMC03Vet

    Meme enthusiast > high capacity enthusiast.

  • DanGoodShot

    I know some people have had issues with thier sf60. Mine has ran flawlessly for the past couple years. I beat the hell out of it too. I will say when I pop rounds out by hand some weird things do happen. But, when used not a single issue. I’d love magpul to do one but I just don’t see how they’d get a polymer one to work. Not without there being some metal anyway.

    • pun&gun

      Thanks to their AK magazine line, they do have experience with making polymer magazines that use metal parts.

      • DanGoodShot

        I’m not familiar with their ak mags. Thats good to know. Maybe they’ll revisit the idea of a 60 round “pancake” mag when they see thats what people want. Not drums. Unless its atleast 100 rounds I’m not going to bother with any over priced drum mag. Thats my feeling on it anyway.

    • John Yossarian

      I own an SF60 and the crazy thing feeds 5.45x39mm without issue. But with all magazines featuring a polymer follower, I always remove the molding lines with a green Scotch-Brite pad. Not sure what problems others were having?

      • DanGoodShot

        I never did that. That’s a great idea though. I opened up the packaging, stuffed it full of surplus green tip and let it rip! If there are any issues they usualy pop up in the first 4-800 rounds(1-2 range days). From what I gathered, people were having problems with nosedives with the very first run of em.

  • Anonymoose

    As an Ohioan who was stuck with 30-round mags until a couple years ago, I didn’t really notice when the coffin Pmag got buried.

    • PK

      That silly law made me annoyed. First thing I did upon leaving from my brief residency there was to remove dozens of wooden blocks from various magazines and drums.

      • Anonymoose

        At least we’re not stuck with 10-round cuckmags.

        • LGonDISQUS

          Whatever you do, don’t google ‘glock chan high capacity’

    • Joe

      Wait, what? I’m in Ohio and I’ve never heard about this. Granted I’ve only been shooting about 5 years but what’s the story?

      • J.T.

        Ohio Revised Code §2923.11(E) used to read “‘Automatic firearm’ means any firearm designed or specially adapted to fire a succession of cartridges with a single function of the trigger. ‘Automatic firearm’ also means any semi-automatic firearm designed or specially adapted to fire more than thirty-one cartridges without reloading, other than a firearm chambering only .22 caliber short, long, or long-rifle cartridges.”

        You could technically own them, but couldn’t put them into your gun (unless it was an NFA registered MG).

        The change happened in 2015.

        • Joe

          So dumb.

        • Anonymoose

          There also used to be various city magazine, salt waffle, CC, and total semi-auto bans in Cincy, Dayton, Columbus, Cleveland, and Shaker Heights, but those were stuck down by preemption.

  • TDog

    “Coffin” mag… because calling these things “milk cartons” isn’t sexy or tactical sounding enough.

    • No one

      Quad stacks have been called Coffin/Casket magazines for literally decades now.

      This is hardly a new trend…..

      • phuzz

        Why are they called coffin mags?

        • PK

          The shape of some of the first attempts at a reliable quad-column magazine, such as the M/31 SMG’s 50rd mag from Finland, led it to being called that in multiple languages. Shorter than a single or double column, squat in appearance, and somewhat trapezoidal in cross-section. It does look somewhat like a coffin.

      • TDog

        Yeah… cause coffins taper at one end like a milk carton… got ya.

        • No one

          Hence the “when inserted in a firearm” comment I made hours ago.

          I know it’s hard, but try reading next time.

          • TDog

            Aw… poor baby.. I didn’t hang on your every word. Must grind that you’re not the center of my universe.

            Get over yourself.

          • No one

            “Aw… poor baby..” -From the person throwing a pigeon chess tantrum that he was proven wrong by multiple people.

            “Get over yourself.” Better Idea, get this concept called “self awareness” for yourself, you seem to be heavily lacking in it right now.

            I guess I can’t expect much from the illiterate though.

          • TDog

            How was it proven wrong? Yeah, it’s an old term – mall ninjas have been around for a lot longer than you take credit for.

            Note, for example, how no one ever came out with a cartridge called “[insert caliber] Weakling” or “[insert caliber] Half-Power.”

            “Coffin mag” is what people called it because admitting that it looked like a milk carton would be too on the nose. Whether it occurred just now or ninety years ago is a bit beside the point given that it in no way looks like a coffin.

            The milk carton, by the way, was invented in 1915 – apparently at least five years before the “coffin” mag. So there ya have it.

          • No one

            You were proven wrong several times on the grounds you thought Casket/Coffin magazine was a mall ninja term despite the fact it’s been used long before the term mall ninja even existed (sorry to tell you, the Finnish Military weren’t mall ninjas, deal with it).

            Your claims to the contrary are completely, utterly baseless and yet you present them as fact when you’ve provided no evidence they are whatsoever despite the burden of proof now being on you, considering everyone here has already tried to hammer through that black hole of a skull of yours that you’re wrong you know, with actual historical citations on the name.

            Quit backpedaling alreadly, you lost, get over it.

          • TDog

            You tend to repeat the same thing over and over, as if saying so makes it so.

            If the Finns went so far as to call it a “coffin mag”, yeah, they were mall ninjas. The damn thing looks like a milk carton. Mall ninja, after all, is a state of mind and not a pedigree.

          • No one

            You literally just stole what I wrote to you and tried to reflect it back on me.

            News flash, 1. you’ve been backpedaling this entire time, 2. you haven’t presented a single piece of evidence to support your ridiculous claims.

            And no, that’s not what a mall ninja is, nor were the Finns or anyone else who made Coffin/Casket mags using the term trying to be mall ninjas, and no amount of you trying to play mental gymnastics will change that fact. try actually looking up what you’re talking about before saying….well, anything ever again preferably.

          • TDog

            I’m surprised… you didn’t use the beloved phrase “pigeon chess.” You’re growing up.

            As for evidence, I have presented it – you just choose to ignore it.

          • ostiariusalpha

            Invented in 1915, yes. They didn’t become widely known though till the production of the cartons became automated, therefore cheap, in the later 1950’s. This coincided with the increase in private ownership of refrigerators also. Before then, only a minority of people in the U.S. knew about that type of paper carton, and virtually no one in Europe did.

          • Tassiebush

            Wow mate I’m having a flashback! I have early childhood memories of milk bottles in early 80s. You’d leave them out to be taken and refilled by the milkman.

    • iksnilol

      They havw always been called that. Simce they sorta resemble a casket when viewed head on. Google “Sites Spectre M4”

      • TDog

        Always… as in right after they figured out “milk cartons” wasn’t at all what real operator spec ops tactical ninja stealth delta green dudes would say or use…

        • No one

          So, as in “term first used as a term in a firearm that predates WW2?”

          I mean, I know you’re being salty about being called out for not actually knowing what you’re talking about and trying your hardest to not accept you’re wrong, but you might just want to stop the whole “arguing just to argue after I was wrong” thing just because of said salt.

          • TDog

            Take a good long look at coffins and a good long look at milk cartons. Just because you don’t think mall ninjas didn’t exist before 2003 doesn’t mean they didn’t.

          • No one

            I guess the Finnish Military circa 20s-30s were mall Ninjas trying to make a quick buck off of civilians!

            Or that, as you failed to see above, the tapered top shape of milk cartons didn’t even exist until the 50s!

            I can’t tell if you’re trolling or legitimately dense as a neutron star, but either way, quit while you’re behind.

          • TDog

            Milk cartons were invented in 1915, so yeah, they decided to go with the sexier “coffin” than calling it a milk carton.

            “See this? It brings death! It fills coffins! See?” As opposed to, “Sarge, should I be sticking a straw in this and sucking out cold milk?”

            Face it: it’s a milk carton mag. Coffins aren’t shaped like that. Never have been. Likely never will be unless you’re a total idiot.

          • No one

            Your logic is stupid and you’re stupid.

            Take a good look at iksnilol’s post right above you and kindly shut up, thanks.

            Also, “total idiot” god, self awareness sure is lacking within you alright.

          • TDog

            Whoa… I’m dealing with a real intellectual here. Come on… work in “stupid” just once more! I know you can! 😀

          • No one

            So you finally forfeited your argument completely and went into full pigeon chess mode?

            Ok good.

          • TDog

            You are in love with that term! You must’ve learned it recently ’cause the way you’re using it, it’s pretty obvious you think it’s the be-all end-all of put downs.

        • iksnilol

          Well,thry’ve been called that since the 20-30’s which was when they were first made.

          It isn’t a ninjaneered name, get over it.

          • ostiariusalpha

            Well, they might have called them milk cartons if it weren’t for the problem that sable top paper cartons didn’t become popular and common until the late 50’s. Guess they just missed their opportunity.

          • Tassiebush

            Man please tell me that milk cartons are another interest of yours and it’s not just something you researched for this argument! I really love that idea man. I’m quite attached to it!

          • ostiariusalpha

            Ha ha, we have a milk processing plant in the same city where I work, I’ve been there several times. The machinery was more generally my interest rather than the cartons themselves, but packaging engineering has its own little intriguing history that I like to examine on occasion.

          • Tassiebush

            I’m delighted! I was kind of hoping you were part of a pub quiz team that dominates the dairy questions section.
            It’s hard not to get drawn into such things. I haven’t been to our local ones but it’s a reasonably big industry here. The Chinese for some reason get all excited about baby formula that isn’t contaminated with melamine so they buy it up from here with gusto.

          • TDog

            No, it kind of is. Coffins aren’t really shaped that way. Milk cartons are.

            And the 20-30’s? Have ya heard how long ninjas have been around? Long enough, I dare say, to ninjafy things since before the 20’s. Just sayin’.

          • iksnilol
          • TDog

            Yeah… that’s a bit of a stretch. You’re gonna have to do better there.

            Here ya go!


          • No one

            It’s a stretch if you’re blind I guess.

          • TDog

            Not really – the magazine needs to be reoriented and have the entire top taken off to be seen as coffin shaped whereas the milk carton is pretty much identical to the quad-stack mag no matter how you slice it.

          • Able_Dart


          • TDog

            I’m just waiting for the day they make a mag that looks like a bundt cake.

            Complete with powdered sugar.

          • izhmash

            Getting a real autistic vibe from Tdog ?

          • TDog

            Autistic? I don’t own any Class III weapons! ;D

          • Brett

            Dude, military names are beyond weird. Google “miliary water buffalo”

          • TDog

            Just Googled it… for some odd reason, I’m now obsessing over the fact that:

            1. They called it a water buffalo in the first place and
            2. Apparently they are for sale.

            Do I need a 400-gallon water tank? No.

            Do I want a 400-gallon water tank? Mmm…maybe. 😀

          • iksnilol

            I don’t see any resemblance. A coffin is wider than it is deep, same applies to magazines.

            The base of a milk carton is rectangular.

          • TDog

            Sure you don’t… sure you don’t…

          • iksnilol

            I literally don’t.

            I think you are obsessed with milk. Do drum mags remind you of milk jugs?

          • TDog

            No, they remind me of either drums, snails, or those old fashioned popcorn poppers you heated over a stove.

          • iksnilol

            But they look so alike, how can they not?

          • TDog

            Wow… this thread really has you tied up in knots, doesn’t it?

            “Mommy! Mommy! He made fun of something I cherish! Make it stop!”


          • iksnilol

            I think you are the one that’s tied up.

            You sick, milk-obsessed man.

          • TDog

            I’ll have you know that I’m also obsessed with Star Trek, losing at chess, and Diet Pepsi.

          • iksnilol

            Diet Pepsi!? HELP, CALL THE POLICE!

          • TDog


          • ostiariusalpha

            The police can’t help you, TDog will just give them a Pepsi and they’ll be on his side; as proven by Kendall Jenner.

          • iksnilol

            I’m glad I bought two of those Finnish bullpup shotguns.

    • LGonDISQUS

      So, if this somehow did catch on decades ago, could it have become trendy to say “HOLD ON, I’M MILKING MY RIFLE!” when reloading?

      • TDog

        That would have been totally rock.

    • Tassiebush

      Dude milk is way sexier than coffins!

  • Geoff Timm

    I’d rather have five or six 30-rounders for the same money. Geoff Who likes to keep it simple, of course if I was doing point defense against a Zed horde…??

    • LGonDISQUS

      I just can’t imagine the difficulty of lugging four Magpul D60s without looking like I have kettlebell sized testicles dangling from a tactical pouch or two.

  • I wonder if the straight walled, non tapered cases of the LSAT ammo would improve the reliability of a coffin mag?

    • PK

      It would certainly make design considerations worlds easier!

    • Young Freud

      Of course, if it’s straight-walled, you could pull a P90 and place the magazine along the barrel axis.

      • The only problem with the P90 magazine is that it is crazzzzzy long due to the space occupied by the bullet flipper at the end. I don’t have one handy but it’s over 10″ long, while a 42rd 5.56 AUG mag is 9.”

        So the layout negates the magazine capacity advantage offered by the 5.7×28, and also makes carrying spare mags a real pain in the ass, as they are both long, and also thicker at one end due to the bullet flipper, so you cannot carry two mags per pouch.

        I really like the P90, but once reloading / mag carrying is put into play, the MP7 style format becomes superior.

  • Obviously the solution is to hire a kid to run around after you with a big canvas sack full of ammo and just stuff handfuls of it up the wagwell while you shoot.

    I wonder how long it’s going to be before someone goes the California Gatling route of designing an upside down AR that just feeds from a big hopper on top, so you can keep shooting for as long as you keep dumping ammo in. It’s not a removable magazine!

    • noob

      Hand cranked, hopper fed, air cooled, tripod mounted, californian-served weapon in 5.56mm.

      • Major Tom

        With a shoulder thing that goes up?

        • Ben Warren

          That would be the rear anti-aircraft sight.

      • LGonDISQUS

        I’m sure you could divert some gas or kinetic energy from recoil to have a rail mounted loose magazine system of some sort.

  • Bradley

    What exactly did they finally explain? That it didn’t work?

    • noob

      Yeah they said they whacked it hard against a rock and it broke. Then they decided let’s do a drum instead.

  • Major Tom

    Meanwhile in (Soviet?) Russia, 50 and 60 round casket mags have been in service with minimal problems for years.

    • noob

      General Kalashnikov baked the idea of not needing a magwell in from the start. Possibly inspired by finnish and russian subguns which fed from drum and coffin mags.
      It’s funny how the soviet philosophy was to scale up a subgun into an assault rifle and the nato philosophy was to scale down a battle rifle into an assault rifle.

      Somehow they met in the middle with a gas operated, 22 caliber, high velocity, high magazine capacity weapon.

    • Young Freud

      I’m going to be contrarian and ask for proof of reliability here. I know we’ve seen pictures of the things everywhere, but Russia holds the same mall ninja aspects as our gun industry. Have any even made it to the United States to be tested out?

  • Big Daddy

    It’s complex, they have to be PVT proof. If a PVT cannot break it than it’s good to go. Anything complex that has more working parts will fail quickly. Taking it apart to clean makes it even more non-user friendly. There’s people with AR15s that do not know how to take apart their mag as it is. So you now will have warranty issues and that could lead to the company saying to these people it was your fault. They then go on Facebook and say your company sucks. Like they did with the Magpul move because they didn’t move out fast enough. Which was an ignorant statement by people who never ran a large company, let a lone a manufacturing one.

    It might work for a well trained military type or firearm enthusiast and that’s about it. I love high cap mags like the D60 and I would not be interested in one. Look at the surefire one, a disaster. They were fails, everybody who field tested them has issues. That’s why I did not buy them. Do they even make them anymore?

    Plus they are heavy to begin with and adding the ammo you have an anvil hanging off your gun. The lighter your weapon the easier it is to get into action. It’s more important to learn how to change mags fast and efficiently.

    • Major Tom

      There’s no such thing as PVT Snuffy proof. If you think something is, clearly you haven’t given it to him or let him have enough time with it.

      The issue of capacity vs reload speed is one where capacity and technology trumps training. A 30 round mag is a step up from 15-20 rounders which themselves are a step up from small capacity stripper clips, en-bloc clips, speedloaders, and small boxes of 5, 6, 8, or 10 rounds.

      If speed loading were so superior at all times, we wouldn’t need anything higher than 10 rounds under any circumstance. And at that capacity, you wouldn’t need mags at all, you could get by with en-bloc/stripper clip-fed rifles/carbines.

      Meaning ultimately a 50-60 round casket mag is superior to a 30 round one.

    • DwnRange

      Not “everyone” – of the dozen SF60s in my inventory I have yet to have an issue with any of the ones I have un-packaged and used, but then it should be noted here I disassemble, clean and clear any rough edges on the follower and inside the mag body and properly polish/lube both the spring and body the SF60 mag after removing it from the plastic it came in – BEFORE USE.

  • The quad stack mag seems to be a reoccurring rediscovery every few decades. Each time they are introduced as some great solution to limited magazine capacity and stick around long enough for them to be used enough for their unreliability to be rediscovered. Its one of the many firearms ideas that get recycled constantly.

    For those that don’t know what I am talking about here is a list off the top of my head:

    Suomi KP/-31 , attempted in the ZB26/30 but given up on, SPIW program, spectre smg, surefire, magpul. there are others but I can’t remember them off the top of my


    • Paul Epstein

      I think what eventually dooms them is the continued existence of belt fed weapons like the M249, honestly. If your sustained fire needs are such that they can’t be met with 30 round magazines, they realistically can’t be met by most guns designed to use those magazines either, even once you’ve added capacity to the mag.

    • No one

      The Magazines on the Spectre M4 work fine from personal experience, It was the gun itself that never sold very well.

      • I have never had an issue with the Suomi magazines in my Swedish K either but when was the last time you were in the field/dirt/mud with it or relying on it for your life? They just are not as reliable for military service.

        • LilWolfy

          The coffin mag for the Suomi was banned from use on the front in the Winter War, relegated to training use only. Preferred mags were the sticks and drums, the drum mag being a copy of the Thompson SMG mag, scaled down to 9mm Luger.

    • FulMetlJakit

      If someone could perfect constant force spring mags I would gladly take “reduced” capacity coffin mags (40<x<60rnds?) if the width/length allows me to use my standard 2x pouches after removing the dividers, and more importantly, they were reliable.

  • Henry C.

    Does anyone have a link to Magpul’s patent on this?

  • Malthrak

    So…aside from “it didnt work the way we wanted” (a fairly obvious conclusion)…what exactly was revealed here…?

  • R3

    But they still won’t explain why the AK74 mag is still unavailable. I got all excited when I saw it in your History of the Pmag shotshow video, but then Patrick and Magpul completely skipped it. I suspect that mag has all sorts of geometry problems that Magpul can’t engineer away. I wish they’d at least explain why.

  • Some guy

    Oh, an update on the Magpul quad stack magazine.

    Nevermind that, how about an update on the development of the Magpul UBR Gen 2?

  • noob

    We need Regular Gun Reviews! “The Glock is American law enforcement finally getting around to the European obsession with 9mm. It’s blocky, but with rounded corners – giving the idea it’s plushy in your waistband.”

    • LGonDISQUS

      I registered a bunch of accounts across social media under “Okay Gun Reviews” but never had the time or passion to actually start.

      • noob

        I’d watch, like, share and subscribe. The world needs more gun humour.

        As AvE would say “until next time, keep your stick on the ice.”

  • Hanzo

    Thank God Magpul isn’t Microsoft. They’d have the product out posthaste, no regrets.

  • Sledgecrowbar

    What if they gave it five or six stacks? Would it work then?

    ::hopeful face::

  • CMD

    Gotta be the car; chicks dig the car.