Magpul’s Quad Stack Magazine

Magpul has just filed a patent application (#20100126053) for a quad stack AR-15 compatible magazine.

The design is quite straight forward. A central partition separates two dual staggered round stacks. Two springs are used, a lower stronger spring and a weaker top spring, which are joined by spring slicer.

The magazine has a constant curve geometry. Interestingly, the transition area (16) is asymmetric in order to stagger rounds correctly.

The follower

The follower is very interesting. Two bails (58a and 58b) are spring loaded. When the follower is pushed against the central partition they part and reveal a hole which allows the follower to descend below the partition.

The patent does not reveal what the capacity of the magazine would be. I would expect it would be around 50 rounds.

The patent application comes on the heel of the announcement from Izmash that one of the major features of the AK-200 will be a 60 round quad stack magazine. It seems 2010 or 2011 may be the Year of the Quad Stack Mag!

A quad stack magazine would be ideal for the M27 IAR. I have no doubt that Magpul will eyeing a lucrative contract with the USMC.

You can read the full patent after the jump.

UPDATE: Drake at Magpul said to me “Unfortunately I am unable to disclose any other info at this time on the product in question.” (more…)

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • Sounds pretty cool in principle. However, I’m not completely convinced that the feeding reliability would be comparable with the current PMags.

  • jake

    Bad….. Ass…..!

  • sturmgewehr

    I remember reading that one of the reasons why the BetaC mag is not recommended for use is that the additional weight of ammo can place a strain on the mag spring. I wonder if there would be a similar problem with this product, thus precluding it from issue for some older rifles.

  • Redchrome

    do you mean the magazine catch spring?
    (I’d chalk that up as one more less-than-the-best design feature in the AR15.)

    This is exceedingly sexy and cool. Sign me up for one!

    It’ll be worth comparing to the Armatac design for a 50-round AR15 mag.

  • Cameron

    I. want. one. NOW.

  • John Callahan

    Wow…Awesome. That would be ideal for the M27 IAR. A 30 round mag is not enough, but the Beta C drum is kind of “too” big, IMO

  • Weaponbuilder

    I’d sure hope to God they put one heck of a mag follower bumper pad on the bottom of this thing!

    Sure would suck to release this mag, have it fall to the ground, shatter the baseplate, and have the unusual internals come flying out the bottom of the mag!

    I’ve already had one Pmag crack its feed lips when it fell free of the magwell during a Tac Carbine course. Not very confidence inspiring in a potentially $90+ ~50rd quad-stack mag, IMHO. (Guesstimating on the price-point)

    I’m sticking with USGI mags with upgraded internals until any teething problems get ironed out.

  • Freiheit

    I hate to nitpick, ““Dual” is an adjective describing the two-ness of something—dual carburetors, for instance. A “duel” is a formal battle intended to settle a dispute.”

    Please consider this constructive criticism, still love the blog and the news it brings.

    source –

  • Bill

    If it works, I’ll buy one

  • Bill

    Dang, brilliant design…

  • Carl

    Anyone has some experience with quad stacked mags? There was one for the Spectre M4 SMG out of Italy. It’s a neat idea, but just so many things that can go wrong. I think you will need very small tolerances in your manufacture if you are to pull it off with any reliability.

  • puppezed

    This remings me a bit about the old Finnish Suomi SMG gasket magazines 🙂

    • puppezed, thanks for the link. I think this design will be much more effective. One follower and it goes all the way up.

  • D

    variable geometry follower, impressive. Opens up in the quad stack part of the magazine, turns back to normal in the double stack part. If they ever come out, would be fun to have 😀

  • root man

    If it works.

  • Mat

    Hmm looks very simmilar to the M4 spectre 4 row magazine developed in the 70’s
    But it seems now that russians will be issuing some with the new AK models.And if they are as reliable as standard mags or drums you can expect to se some with AK ‘IAR’ RPK ,evne tough drums are hard to beat on RPK ,on ar platform they ar not that practical due to magwell

    As for 4 row magazine year ,i doubt it ,to much weightwith 50rounds. ,M4 sprectre 9mm submachine gun had a 4 stack magazine both 30-50rnd versions allready back and was buit in the late 70’s but no one else used it.

  • Anton

    I’m liking this, just two of those mags and you got a shed-load of firepower.

    Will this be made for .223 or .308?

  • jaekelopterus

    Catchin’ up with the Ruskies! I <3 Magpul.

  • Trango

    That M27 IAR was the first thing that came to mind when I saw this design. That rifle and this mag could really set forth a series of positive changes.

    However, those familiar with this industry know that it can take a while for a concept to become a fully functional, battle ready, product….the ACR comes to mind.

    I’m guessing that if Magpul gets this mag off the ground, and I’m sure they will, we won’t see it available mainstream until 2012. That’s just my hunch.

  • ben dejo

    It seems that everyone has finally read the patent that SITES did for their M4 SMG way back in ’80s. It only took 25 years for the industry to make the leap. This to me is in no way even remotely exciting as this “innovation” should have taken no more than 5 years to achieve (i.e. this this should have been perfected no later than 1990). Even then there is room for improvement as this is a hybrid design that is forced to work with the existing AR type receiver when quite clearly it should be replaced with a better design.

  • MrMaigo

    hmmm, you’d think C Products would have figured it out first

  • Ryan Warner

    Mag weight fully loaded would be a little less then 2lb! I’d hate to have to lug those around. Plus the size of the mag pouch would be huge! Impractical if you ask me…cool, but impractical.

    @sturmgewehr: Another reason the C-Mag isn’t used is the noise created by the rounds rattling around inside the mag when you walk or fire the weapon.

  • Andrew

    I had this as an idea two years ago only to discover it was patented a while back. VERY similar to prior art but I can guess at where magpul will say they are unique. Search google patents for quad stack magazine (original patent is for a 9mm type device).

    I personally decided that 30 with easy change was good enough and the next step would be belt feed 🙂

  • Aurelien

    Looks like it works like the Izmash quad stack for AK-74 used by the russian army.
    Perhaps a little less basic as a design.

  • mkrautz

    When magpul makes a pile of crap after eatting chili you all want it.

  • Nathaniel

    I approve.

    LSAT’s rifle design, also revealed at NDIA, uses a quad stack mag.

    They’re apparently the Next Big Thing, and I am very pleased.

  • Jack

    The Russian AK-200 has a quad magazine. Anyone know the details?

  • I bet that Bushmaster manufactures it and sells it for $500 6 years later.


  • Andrew

    How about one for the mini 14! I’ll take two.

  • El Duderino

    Pfft quad-column mags are SOOOO 1980’s…

  • Jason

    It’s agood thing we don’t need gimmicky crap like this in California.


  • That looks amazing to say the least!

    “…separates two duel staggered…”

    “Dual” I think you meant.

  • Lance

    The Russian had a simular idea with the AK-74 mag it didnt work. It was too heavy loaded and bulkey to get ride of 30 round mags. For sport shooting this would be cool. But not really a practicle idea for LE or military applications.

    Mabie its for the M-27 IAR.

  • Carl

    Here is more about the Finnish/Swedish four stacker: 1/3 down the page
    Apparently not very successful. I agree the design looks good though.

  • Mack Hughes

    This is a freaking vertical, straight beta that already has problems, the ammow rows don’t like to converge once the ammo is slightly fouled, are you going to have to lubricate this to work also?

  • I’d rather have five of these mags than eight standard 30 rounders. The overall carry weight would be about the same, since I’d be carrying almost the same amount of ammunition (250 rounds with the quad stack, 240 with the standard). The advantage would be that I’d have to make half the mag changes, saving me time. Magpul is all about shaving those vital seconds off of tactical tasks that could save your life. Every second I’m not spending changing mags I’m sending rounds down towards my enemies.

    That being said, if magpul does produce this I’ll wait to see if their are any teething problems. Considering that Magpul rarely releases products before they believe in them, I doubt they’ll release a product before it’s ready. Look at the BAD lever, took for ever for them to perfect it but they would rather keep people waiting and pefect something than put lives at risk.

  • jdun1911


    Here how springs works. Magazine springs (good) elastic limit goes beyond holding their capacity. For example, a full loaded 30 rounds magazine will not damage or weaken the spring because the load does not exceed the spring elastic limit. So basically if the spring is good, the magazine can be full loaded without any worry of malfunctions in your lifetime and beyond.

    Other than rust, what weaken the elastic of spring is the compression and decompression of the spring.

    The heavier the load the strong the spring has to be. The spring needs to keep up with the cycle rate of firearm. If it can’t than malfunctions will occur.

    The reason why military do not use 100 drums magazine is 1. They are easily damage and thus cause malfunctions. 2. Because of the heavy load, the spring will get weaker faster over time with use. This might not be problem if you’re going semi-auto but at full auto or burst the spring will not have the strength to keep up with the fire rate.

    40 rounds magazine has been proven to be reliable via competitions so I doubt these magazines will have any problems. However I do wonder what type of pouch will fit it and how durable if it drop to the ground full loaded.

    Anyway from what I understand their 40 rounds magazine will come out this fall and retail below $25. I’m going to get few of them because at that price it is a steal. Most 40 rounds magazines cost over $80. The 3 guns people are very happy by the price point.

    I’m still waiting for durable .22lr magazines tho.

  • Thomas M.

    while an interesting idea, it give me pause. Losing, breaking, or getting a single 30 round magazine can be, depending upon circumstances, costly to absolutely dangerous. What would losing, braking, or damaging a 60 rounder be under the wrong circumstances.

  • Vak

    Honeslty, I don’t get why people are so excited about this.

    – New pouches will have to be designed, and I bet they will be expensive. At least the AK 60 rounds magazine is just as big as two AK 30 rounds magazines, so you just have to get a 2 mags pouch and call it a day.
    – The AR magwell severly limits the eficiency of these mags. I’m going to compare it to the AK magazine again, so bear with me. An Ak 60 rounds mag is going to be just as long as a classic 30 rounds mag, and the magazine capacity will be multiplied by two. But because of the AR magwell, if they don’t increase the lenght (which they surely won’t, because shooting prone with an excessively long magazine is never fun) and stick with a “standard” lenght, I don’t think they will be able to double the mag cap. Maybe put 15-20 or so more rounds.

    Well, that was my two cents.

  • BigHead, you may not be too far off on that $500 price 😉
    One AK74 Quad stack was for sell on Gunbroker that started at $600 and closed at $900 without meeting reserve.

  • subase

    They probably should have made a 30 rounder that is as short as a 20 rounder. But I guess that’s not tacticool enough these days.


    I doubt it will only be a 50 rounder. Why go to all the design trouble to only make a mag that holds 10 more rounds than their 40 pmag?

    This design could be modified inorder to manufacture mags to hold many different amounts.

    IE 20rnd size= 40
    30rnd size = 60
    40rnd size= 80

    These are only examples and Im basing this off of how Magpul currently releases there PMAG product line up.

  • Follow up to my earlier post if anyone is interested:

    Patent #4,589,218, filed Jun 26, 1984, titled “Multi-stack cartridge magazine for firearms” looks like some STRONG prior art. Will magpul say the follower doesn’t articulate like theirs? Sure, but there is prior art for that: filed Aug 13, 1969, titled “LARGE CAPACITY MAGAZINE” is a 4 column with an articulating follower (but not the split, two spring design of the later patent).

    I don’t know magpul… combining two old patents sounds pretty obvious to me; I think you are patenting something that isn’t unique enough (but hey, I’m not a patent attorney).

  • Husam

    Why is magpull not sold yet to a big multi billion company?
    These guys come up with really innovative things

  • Phaz

    Copying the Russians?

  • krklek

    Well, I see that Magpul has STOLEN the Russian’s patent on the winged follower!!! Yeah, I can’t wait to see how many of Magpul’s quad magazines fail due to the extra weight since they fail to put any metal in their mags.

    And I know for certain if they even try to make these for AK’s the mags will be torn apart with the front or rear or both mag lock tabs being ripped from the mag body. WHY? GO to and watch some of the “drop” tests they do on REAL “MIL-SPEC” mags. Magpul fails these tests horribly!!!!!!!!

    Magpul produces these for the CIVILIAN market where one is expected to stand or sit STILL while shooting. Case in point is why they brought out the eMag, wherein the pMag failed in simple “insertion” tests. They send mags to market that won’t even fit mag wells?? They can’t look at a spec sheet and make their mag to the proper measurements?? DUH!!!

    Don’t get me wrong, Magpul does have some very nice products, but when it comes to mags – THEY SUCK!!!! And when you are fighting for your life, a bad mag is the last thing you want………

  • krklek

    Husamon 13 Jun 2010 at 9:16 am link comment

    **Why is magpull not sold yet to a big multi billion company?**
    These guys come up with really innovative things – end Quote.

    **See my post directly above this one and you’ll see WHY no one has purchased the company. They SHORTCUT the hell out of products!!! What are a bunch of guys complaining about mags going to do – sue Magpul?? That would get about as far a fart in church!!

    But, on the other hand, if they had a 200 million dollar contract say, with the Government and they shortcutted, the government would tell them to go and “pound salt”!!! MAKE THEM either fix or resupply our troops with GOOD products. Can you imagine having a HUGE contract and then your products start failing at a fast pace and you had to completely re-engineer and manufacture the entire contract?? They’d go bankrupt in a day. And of course, that would be the end of Magpul.

  • sam

    I hate to feed a troll but krklek your wrong on a few points.

    One “GO to and watch some of the “drop” tests they do on REAL “MIL-SPEC” mags. Magpul fails these tests horribly!!!!!!!!”

    On kvars website the videos do not show a test of a Pmag, and all tests I have witnessed and participated in, Pmags have been the toughest to break.

    Two “Magpul produces these for the CIVILIAN market where one is expected to stand or sit STILL while shooting. Case in point is why they brought out the eMag, wherein the pMag failed in simple “insertion” tests. They send mags to market that won’t even fit mag wells?? They can’t look at a spec sheet and make their mag to the proper measurements??”

    Magpul is a civilian company, but many of the mags they produce are bought by our men and woman serving over seas out of pocket because they are better than GI issue mags, You are correct in that Pmags do not fit all STANAG mag wells like that on the SA80, however they are not called a STANAG complient magazine they are designed for use with the m16/ar15 mag well, which is shorter than other mag wells, the ring around the mag acts as a seal that mates to the well, preventing dust to enter. hince why they do not work with all STANAG rifles.

    lastly I think were you got confused in the drop tests were Promags, not pmags. pro mags are a very diffrent animal, and I don’t know anyone who trusts them 100%. but any fighting man i have talked to, who used Pmags in combat trusts them more than Gov’t issue.

  • Cameron

    Thank you Sam.

  • sam

    No thanks needed Cameron, however you’re welcome just the same.

  • Keith Applegate

    After perusing the MagPul paten application I think I understand.

    The MagPul Q-Mag is a staggered feed, single follower, a single spring system and a dual cartridge compartment design.

    The Suomi is a single feed, dual follower, a dual spring system and a dual cartridge compartment design.

    The Russian AK-quad is, as it was explained to me a while ago, a staggered feed, single follower, a single spring system and a single cartridge compartment design.

    So, while I see a lot of similarities I also see that MagPul has combined them in a rather innovative arrangement.

    Having fired a Suomi with the famed “coffin” mag I can attest that they functioned extremely well. I have personally never seen one fail to function. So I suspect that the dual cartridge chamber idea is sound.

    However I was also told by the gentleman who owned that particular Suomi that you had to make sure that both springs were of equal power or there would be malfunctions and sometimes the mags would “get out of time” and sometimes one side would feed faster than the other.

    I also think that the huge open cartridge compartment of the AK-Q could cause some problems if, for instance, a gun with a partially loaded mag was dropped or otherwise sharply jolted, the weight of the ammo briefly compressed the feed spring and thusly allowed the cartridges to move about into less than optimum positions for feeding.

    And it’s pretty much a foregone conclusion that with regard to dual column magazines staggered feed is superior to single feed. Thompson mags feed better than Grese Gun mags. Uzi Mags feed better than Sten mags. Although single feed mags can be very reliable as well.

    The Q-Mag with its dividing wall creating two cartridge compartments looks to be the best of all worlds.
    Combining all of the best features;
    – staggered feeding
    – single follower
    – single spring
    – dual cartridge chamber

    So, perhaps it will be recognized as a superior version of the prior art and MagPul will get them into production in a timely manner.

  • charles222

    Any more news on these? I’m particularly interested in width, as that’s the real determining factor when wearing an IBA/IOTV.

  • Keith Applegate

    Based on the patent drawings, if they release it as a 50 round magazine, I suspect it will be the same length and twice the width of a standard 30 round P-Mag. So any pouch that will hold two P-Mag30 will hold a single Q-Mag.

    Which means you can carry 50 rounds in the space of 60. BUT you have to deal with one less mag change.

    As to why make a magazine that only holds 50 when they have already announced a 40 rounder? Well it boils down to length. A 30 round is already difficult to use when firing prone. IF you are wearing a chest rig full of mags then your prone is a little higher. But all current 40 round mags, and the P-Mag40, are simply too long for any prone shooting.
    The gamers will like them for competition where they shoot standing or moving. The 40 rounders are also good for home defense. A CMMG is what I currently have in my rifle. I figure if I can’t get it done with 40 then I need air support.

  • charles222

    Thanks, Keith. I was suspecting this was going to take up about the same amount of space as two 30-round Pmags.
    And I’ve never had a problem with using a 30-rounder in the prone-I take it you’re short or something? :p

  • charles222

    Well, the announcement of the M4A1 and it’s full-auto trigger group becoming US Army standard has made these more interesting to me-anyone have a clue as to when they’ll be actually available?


    When will they be available?

  • Ramdom Guy

    Guys, is the Pmag a new idea? No, it’s a plastic the AK-74 had them. Is it a great idea? Yes. Magpul doesn’t release just 100% unique products, just products that work well. The patent seems like it’s for the general idea, so they could make smaller capacity mags. If these mags are 50 rounds they might fit a double AR-15 mag pouch.

  • charles222

    It should fit a double-the height of the magazine won’t be any different.

  • Sam Suggs

    me want