Magpul Quad Stack — Saving the IAR

The Firearms Blog has a post on a patent filing from Magpul Industries for a so-called “quad-stack magazine.”

Basically, as TFB puts it, the slightly wider magazine accomodates what looks like about 50 rounds using two springs and a divider to weave the 5.56 rounds in.

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 is asymmetric in order to stagger rounds correctly.

Check out the post for more schematic detail.

I raise this because it adds to the Marine Corps Infantry Automatic Weapon debate that’s swirling quietly in the halls of Quantico and the Pentagon. I’ve heard of grumblings from within the Corps that the IAR is a waste of time and money and doesn’t really add to the capability of the fireteam. Primarly complaints stem from the lack of firepower offered in a 30 round magazine. Well, as TFB points out, the Magpul magazine, if it works, could be the answer that corrects the problems with C-Mags and answers the concerns of grunts who want the amount of led the SAW carries.

One thing is for sure, the Corps is still going ahead with the IAR program, which they call the M27 — it’s just a matter of how many and for whom at this point.

  • Since this beast of weapon is going forward I propose that we simply replace the M16A4 and M4 with it. We can have entire squads of automatic riflemen…

    Seriously though. That is the one weak point in the M16A4…it has the range. The new bullet will enhance the lethality of the weapon since the IAR is only a tidbit shorter than the M16A4 and we would again get back automatic fire.

    As a replacement for the SAW hell no. As a replacement for the M16A4? Ok, I could live with that.

  • Tmash

    I love the IAR concept and wish the army would go with it. The SAWs a pain in the a$$ to lug around in a confined space and cleaning is a 2 man task after hvy usage. And besides if i want a belt feed weapon for hvy suppression id rather have the M240 firing the 7.62. Has greater killing power at distance.

  • Sam

    Way to go MAGPUL. they are some of he most innovative weapon designers.

  • howard

    Enter text right here!don;t know about you guys but i always preferred MORE ammo than less.
    whether the weapon has the range and accuracy is another issue.
    Magpul seems to have good to go gear.
    i kind of like the comment about everyone an auto rifleman.
    more ammo longer range higher kill go home earlier

  • STB71

    It’s interesting that the original weapon specs for IAR-to replace the SAW-were from a weapon that already existed, the Ultimax from Singapore. But as soon as the call went out, US weapons makers immediately started coming up with their own-based on M16 paltaform, adding complexity to a weapon that already has enough problems with reliability. FYI-reliability issues w/SAW in desert is what drove the call for a replacement to begin with.

  • Johnny Parisi

    all i know is i would rather have 50 rounds then 30

  • M.G.Halvorsen

    Me too, there, Johnny! 50 rounds in the magazine well beats the hell out of 28 in the rifle and the rest in the ammo pouch! Let the haji stop to reload…

  • Except that the winner for the IAR is H&K…a European parent company…

  • Infidel4life

    the problem in a-stan is DISTANCE. the IAR would be great in urban settings, but it has limited range.

  • glebur

    The IAR is actually the H&K PISTON operated 416, which is about to be shipped in August to civilians as the MR556.
    The reason that higher firepower can be achieved with a 50 round mag in the 416 versus a 30 round mag in the DIRECT GAS IMPINGMENT M4 is the operating system. The piston 416 can handle more rounds per minute longer than the M4…so a larger magazine capacity makes sense. IF the IAR remains PISTON operated.
    The piston system keeps the bolt cooler and cleaner, allowing the 416 to keep running while the M4/M16 suffers a malfunction. However, if the troops all “want the firepower of a SAW”……what goes along with that is a heavier barrel, in order to withstand the heat. And THAT, the troops would not like the extra weight. Be careful what you wish for…….

    • daniel

      That is absolutely untrue, you sir have no idea what your talking about, I challenge you to produce any citable information that supports any of your assertions. The truth is that yes the piston gun will be cooler it doesnt matter and M4/M16 will not malfunction because it is hot, that absolutely call of duty lack of knowledge about the weapons system I really hope your not in the military. I dont think you know much about either the DI or stroke pistons. The barrel on the M4 will actually rupture long before you have an issue with the gas tube or heat in the receiver. The limiting factor on the ROF of either weapon is how hot the barrel/chamber are the method of moving the bolt has nothing to do with it. Cool and clean have nothing to do with the operation of the weapon lubrication does. a clean non lubricated weapon with have malfunctions and a dirty lubricated one will not.

      additionally you might want to look into carrier tilt and the cracked receivers on the 416s. Like I said you have no idea what your talking about, nice try to portray yourself as an expert though.

      • Hey Daniel, let’s keep it civil here, bro…no need to belittle people unless they’re burning ‘ol glory or something, ok?

      • glebur

        On the 65,000 round USMC test, the M4 suffered 4 times the amount of malfunctions than the HK416. “Citable fact”, with the XM8 suffering the fewest malfunctions. Apparantly you are referring to recent events in Afghanistan which challanged the old belief to only lubricate when clean, as opposed to the new belief to literally saturate the M4 bolt/chamber even when dirty, as this lubricaton will aid in reducing malfunctions in the M4. As the very purpose of lubrication is to reduce friction, OF COURSE lubrication will help ANY firearm. Again, the 416’s cooler and cleaner operating system provides a distinct operating improvment over direct impingement. The above reference to the 65,000 round test is the USMC test which selected the 416 as their IAR. The 65,000 test IS the facts. The lower malfunction rate is the result of the piston operating system keeping heat and residual fouling away from the bolt and chamber. The stress imposed on the locking bolt lugs is extreme, which resulted in chroming the chamber. So, this problem was noted 40 years ago with that improvement on the M16A1 over the M-16. While there are other factors affecting the efficiency of the rifle, the piston remains the most significant improved recently made.

        • daniel

          I think you need to do some professional reading. Start with Pat Rodgers and get back to me. The test which I assumed you would mention and conveniently did not mention the total amount of failures for dramatic effect simply proved that both are very reliable firearms. Since you dont apparently know what citing is you have to actually name the source your using not just refer to “some test”. May I ask why the 416 also has a chrome chamber as does every modern firearm if there’s some ar specific issue?

          In the ARMY 60,000 round test the m4 has 882 stoppages and the 416 223. not a big difference in 60000 rounds. Now could you enlighten me about this Marine test of 65000 rounds you know of? Not to mention in all the test inferior petroleum product lubes were used. Firearms haven’t really advanced in the last 50+ years however lubricants sure have, that where the discussion should be.

  • John Buol

    >> I’ve heard of grumblings from within the Corps that the IAR is a waste of time … Primarily complaints stem from the lack of firepower

    It is sad when Soldiers and Marines don’t understand the difference between firepower and volume of fire, or the role of an automatic rifle vs. a machine gun.

    The FN Minimi (M249, L108/L110, F89, or Minimi M2) is a good machine gun but a clumsy automatic rifle. The best way to demonstrate this is to force troops assigned as automatic rifleman to first qualify on their respective rifle course(s) to the exact same standard with their assigned weapon.

    In the US Army, that would mean automatic riflemen would first zero to standard at 25 meters, then shoot the three table qualification course with 20, 10 and 10 rounds (RETS, KD or Alt C), SRM and SDM course with their M249, NOT with the M16/M4. After shooting a passing score as a rifleman with the assigned weapon, the automatic rifleman then qualifies on the Automatic Rifleman course.

    Every good shooter realizes the US Army qualification courses are broken but even a poor rifleman has no problem passing them. Forcing an automatic RIFLEMAN to qual with his weapon as a both rifle and automatic rifle, the way it SHOULD be, will quickly point out the M249 flaws in this role.

    Fast X,
    John M. Buol Jr.

  • Johnny Quest

    Replacing a belt fed weapon with a magazine fed weapon is questionable in and of itself, but to replace it with a bastardized M16 adds insult to injury. I would suggest the MK46 or preferably Knight’s Stoner LMG and proper training to save the day.

    The HK IAR will do nothing that a similarly configure M16A5 wouldn’t do in a lighter and more accurate package. Modern coatings i.e. Fail Zero type on internals will help in function, lubrication, and cleaning.

  • >> Replacing a belt fed weapon with a magazine fed weapon is questionable in and of itself

    Why? We’re talking about Automatic Rifles here, and NOT about machine guns. Two different applications. Most soldiers and marines don’t understand the difference, hence the confusion.

    RUSI conducted a series of live fire suppressive fire tests and found the magazine-fed L86 outperformed the L110 (FN Minimi.) Their results were published and publicly available online.

  • APAC

    Surefire makes 60 and 100 rd double stack mags. They seem to do well so everybody will reinvent the wheel! Drum mags no good? Follow cleaning/care instructions and everything seems to work!