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    M27 IAR

    Since we picked on the Army most recently, I thought today we could discuss the adoption of the M27 IAR as the standard Infantry rifle by the Marine Corps.

    For those unfamiliar with it, here is the Wikipedia article:

    https://en.m.wikipedia.org/wiki/M27_...utomatic_Rifle

    ​In addition to the M27, the Marine Corps has been required to drop the mk318 SOST round in favor of M855A1, which necessitated adopting Pmags as the standard to prevent the new round from damaging rifles.

    ​​​Relevant articles:

    https://www.thefirearmblog.com/blog/...-0-ammunition/

    https://www.army.mil/article/48657/e...formance_round

    https://www.marinecorpstimes.com/new...-m855a1-round/

    https://www.realcleardefense.com/art...et_114140.html

    Feel free to discuss, bitch and moan, whatever. The fun part about being armchair quarterbacks is that we don't have to hump this crap around at boot camp. If these discussions are interesting to you guys, let me know and I'll try to keep introducing new topics periodically.
    "No. Listen to me because I know what I'm talking about here." -- Hannibal

    #2
    I don't like PMAGs. I think they get too much wear too fast. I guess if you are considering them a disposable, it's OK... seems like a lot of wasted money, though.
    Consider for a moment that there is no meme about brown-haired, brown-eyed step children.

    Comment


      #3
      I love Pmags. They’re lighter, easier to load and they count your rounds for you. I understand that they’re not as robust but it’s trade-off I can live with.
      Ne Obliviscaris

      Comment


        #4
        I think that if the Marines on the ground, who have used the weapon in combat, like them, then they are a good thing.
        Falling for Judo since 1980

        "You are wrong. Why? Because you move like a pregnant yak and talk like a spazzing 'I train UFC' noob." -DCS

        "The best part of getting you worked up is your backpack full of irony and lies." -It Is Fake

        "Banning BKR is like kicking a Quokka. It's foolishness of the first order." - Raycetpfl

        Comment


          #5
          I think the IAR is a dumb rifle. They tried to back door it in by pretending it was a replacement for the SAW. This resulted in the original RFP calling for heavy profile barrels. Combine that with the fat fucking quad rail and the new gas system and it's absurdly front heavy. This thing is a fucking relic of the early 2000s and I don't think it's an improvement over the M4A1 in most ways. The 14.5in URGI upper from Geissele or something similar would have made much more sense. It's fucking 2020. Give everyone an MLOK rail and an LPVO already.

          Comment


            #6
            Well it's been a few days and not much interest in this thread, so I'll go ahead and share my thoughts:

            The development of the H&K 416 is interesting. Larry Vickers is a big fan of piston guns for certain applications, and he played some insider baseball from 1st SFOD-D and then moved over to H&K to get his design finished. The requirements were that the rifle needed to be reliable in austere and diverse environments, feed almost any kind of ammo, run suppressed, run full auto for long periods of time (a DI gun's gas tube is by design the weak point and will break well before any major damage to the rifle occurs most of the time), and not be picky about barrel length. To Vickers' credit, he makes no claims that this system is universally better than the Stoner system (technically an internal piston but mostly called DI) that the AR15 uses. He simply stated that it met the requirements his unit needed better than a standard M4. He's done tons of interviews and Q&As on this subject.

            Everything he said is true. There are some benefits to a piston gun. But there are also drawbacks. Here are some relevant ones:

            The rifle will be heavier overall, and the added weight shifts the center of gravity forward. Generally not ideal for a 20" rifle with a relatively heavy barrel and long, robust rails. Guessing with optics, night vision aiming devices (if used), flashlight, etc, you are looking at a 12ish lb gun. Probably more if they use suppressors. Now looking at 13-14lbs. Most of that weight is out front.

            I cannot speak to where the gas port is located in the M27, but I assume probably not as far out as it would be with a rifle length system. Maybe I am wrong there. Regardless the system is likely to be overgassed, and recoil will be harsher than with a DI rifle length gas system. More reciprocating mass, more carrier tilt, more bcg drag, etc.

            Piston guns start exerting force on the bolt locking lugs almost instantaneously as the bullet passes the gas port. This makes it harder to control precisely the timing of when the bolt unlocks, which means a piston gun tends to unlock under higher pressure than a DI gun. That can lead to more sheared cases, broken extractors, sheared bolt lugs, etc.

            Bolts in 416 style guns tend to break faster than DI rifles. This is just a fact. It is related to the totality of pressure exerted on the system and the imprecise system timing that comes from adapting a DI system to short stroke or long stroke piston operation. Factor in the somewhat higher operating pressures of M855A1, and I suspect Marines will be replacing a lot of bolts.

            Maintenance with a piston gun is a trade-off vs DI. A piston gun needs less day to day maintenance than a DI gun, but they tend to be harder on parts overall. You can see this with an AK vs an AR. AKs will run for long periods of time without maintenance, until they don't anymore. When piston guns go down, the failures tend not to be of the immediate or remedial action variety. Not a problem for Delta Force's budget and MTOE, but I'm not so sure about the Marines. Instead of replacing bolts on a schedule of say 10,000 rounds, the Marine Corps could be replacing them at 5-6,000. Extractors, ejectors, even firing pins don't last as long due to the greater overall operating pressures of the system.

            It is entirely possible that H&K has solved some of the teething issues of the 416 operating system, or that the Marine Corps is aware of the issues and has planned for the greater overall operational expense of using the M27. But I'm not so sure that is the case with the introduction of M855A1 when the M27 was vetted with mk318.

            PMAGs I have no problem with. They work well and then instead of bending like aluminum mags do when they are overtaxed, they break so you know you can't use them. They are what I use for work and so do most. Aluminum mags are okay, as are the Lancers. But most use pmags nowadays.

            I am glad that the Marine Corps like their new rifles, but I can tell you that most U.S. organizations that adopted the 416 style rifles have since dropped them in favor of DI guns. I think they will like them for awhile, but I'm not so sure how they'll feel in 5-10 years after Snuffy starts getting a beat up old rifle instead of a shiny new one.

            One possible upside: M855A1 fragments violently down to AT LEAST 1800 fps. It does not have the best BC, but from a 20" barrel it will likely have good terminal effects out to 500-600 yards. That said the majority of engagments in war take place inside 300 yards. A 14.5" barrel will be fine for around 400 yards, and if I recall correctly even the crane 10.3" barrel is fine at 300+y I don't have good DOPE on M855A1 from various barrel lengths but it supposedly mimics M855 velocity and trajectory once you get past 200 yards.
            "No. Listen to me because I know what I'm talking about here." -- Hannibal

            Comment


              #7
              One alibi: piston guns tend to be less picky about getting waterlogged than DI since there is no gas tube to get clogged up. Given that Marines tend be responsible for amphibious warfare, that may be a real upside.
              "No. Listen to me because I know what I'm talking about here." -- Hannibal

              Comment


                #8
                I’m always interested in these threads, I just don’t have much knowledge about this particular platform so I’m here to learn.
                Ne Obliviscaris

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