Why the M2. 7 IAR Is NOT the Right Rifle for the Marine Corps. Since its introduction in 2. Marine Corps M2. Infantry Automatic Rifle has proven itself as an effective support weapon that offers more firepower and range than the Corps other squad level weapons, the M4 Carbine and M1. A4 Rifle. This good reception has led many within the Corps to reach an obvious conclusion The USMC should simply replace their M4s and M1. A4s in the Infantry Battalions with M2. IARs. This idea gained so much traction that the USMC has experimented with arming an entire battalion with IARs, and even released an RFI to the industry for 1. IARs. To explore this idea further, I sat down with an anonymous small arms subject matter expert to discuss the M2. IAR, its potential as an infantry weapon, and other possibilities for the next Marine Corps infantry weapon. Together, we came to a surprising conclusion The M2. IAR is not the right infantry rifle for the Marine Corps. In this article, I will lay out the factors that led us to this conclusion, and suggest a potentially superior alternative. Before we talk about why the M2. M2. 7 brings to the table as a fighting weapon. To start, versus the M4 Carbine and M1. A4 Rifle, the M2. IAR has a superior barrel and handguard system. The M4 Carbines barrel is made of the same 4. World War II. In the M4, this steel is button rifled, heat treated to between 2. Brinell approximately 2. Rockwell C and then chrome lined. With the M2. COLTS MANUFACTURING COMPANY, LLC REVOLVERS DOUBLE ACTION, SWING OUT CYLINDER gun model and pricing information. Colts Manufacturing Co., LLC, announced at the 2016 National Rifle Association Annual meeting that they would be introducing new semi automatic. Aubert Duval chrome molybdenum vanadium steel, cold hammer forged to give a tapered bore, and heat treated to 4. Rockwell C, then chrome lined. These material characteristics, especially the heat treat, give the barrel exceptional life and accuracy, and it is easily this factor which is most attractive about the M2. In addition, instead of the M1. A4s and M4s classic delta ring system, the M2. For the Marine Corps, the ability to make accurate hits from any position whether shot slung, from a barricade, off a bipod or pack, etc without substantial POI shift thanks to a free floated barrel unit is value added for each rifleman. Together, these features mean, simply The M2. C8679c__07982.jpg' alt='Colt Trooper Mk V Serial Numbers' title='Colt Trooper Mk V Serial Numbers' />M4 Carbine or the M1. A4 Rifle. A rifle that maintains its accuracy and precision longer is one that gives more hits, better suppression through closer misses, and overall greater combat effect. Given then that the M2. Marine Corps adopt it The reason at its heart lies in the fact that the M2. RFI. It is not that the M2. Infantry Automatic Rifle program was made public, substantial commercial off the shelf COTS improvements have been introduced that could provide a weapon of equal or greater capability to the M2. Even better, by upgrading the M4 Carbine various engineering shortcomings inherent to the M2. This sort of improvement could be achieved via a depot level or upper receiver group upgrade program to the existing M4, which opens a number of procurement avenues for the Marine Corps that otherwise would be closed if the M2. Sole sourcing the M2. Instead of learning from the Corps experience with the IAR and implementing the best possible fleet solution to provide the required capability to the Infantry, they would simply be sticking a ring on their first major crush. The M2. 7 does pave the way forward, but it itself is already dated technology. A more sound approach would be to leverage the competitive environment to procure something better, lighter, and cheaper. One area where a new rifle might improve over the M2. Our source told TFB that with M8. A1, the M2. 7 achieved an average bolt life measured to the first lug shearing off in official high round count tests of 6,0. In those same tests, the M4. A1 achieved a barrel life of just 7,0. However, the M4. A1 Carbine beat the M2. One M4 bolt even went 1. As I will elaborate below, this disparity in bolt life is the result of something peculiar and inherent to the M2. ECPs to rectify the problem. For the M4 Carbine, however, even better bolt life than current could be achieved via simple drop in upgrades and improvements at very low cost. The reason for the M2. From its inception, the HK4. M2. 7 belongs was designed as a short barreled rifle, an industry driven effort to create an alternative to the early Mk. Close Quarters Battle Receiver. To achieve the reliability needed, Heckler Koch dramatically increased the gas flow to the HK4. This improved reliability with the 1. H K Navy steel magazines of the original requirement. Since then, the HK4. This has led to an overgassed situation, resulting in high cyclic rates and increased wear, a situation which is exacerbated by the rifles short stroke piston driven operating rod system. In detail, the HK4. Stoner direct impingement. This means that if gas is not aggressively vented early such as via the uncorking of the bullet from a short 1. In the longer barreled HK4. M2. 7, this causes the bolt to unlock prematurely at a point when the pressure is still high, and unlike direct impingement AR 1. All this together results in higher lug stresses and lower bolt life for the M2. M4 Carbine, in addition to higher cyclic rates which require more tightly sprung and more durable magazines which can keep up with the fast moving bolt group. Aggravating this problem, the M2. M4, bolt groups be replaced as a unit. This means that when the bolt shears a lug, the entire bolt and carrier assembly must be removed and replaced with a new unit. Ideally, a new upper receiver for the M4 Carbine would incorporate a barrel of similar construction and materials to the HK4. Further, it could incorporate new bolt treatment techniques that could dramatically improve part life far beyond the current norm, substantially increasing the maintenance interval for this part. Another one of the chief advantages of the M2. IAR versus its stablemates is its fire control group. In lieu of the M4 and M1. A4s trigger groups which provide safe, semiautomatic, and 3 round burst settings, the M2. IARs fire control replaces the burst function with a fully automatic provision which allows the rifle to be fired for extended bursts. This not only provides an increase in firepower, it also improves the consistency of trigger pull and prevents malfunctions that can be induced by the burst mechanism of the M4 or M1. A4. However, as part of this package, the trigger group of the M2. This feature carries with it the side effects of higher bolt carrier speeds via less hammer delaying effect and reduced disconnector life. Since the selection of the M2. IAR, newer select fire trigger units for the AR 1. Perhaps the standard bearer of these triggers has been the Geissele Super Select Fire SSF trigger, which already has a national stock number NSN and is drop in compatible with the USMCs existing M4 and M1. A4 fleet. That one modification, together with other upgrades, would bring a degree of precision and firepower to those weapons equal or greater than the M2. IAR. The free float rail of the M2. However, even it is dated by todays standards, thanks to the advent of negative space mounting systems which were in fact pioneered by Heckler Koch, but that is another story like M LOK. The M2. 7s Picatinny type free float rail is heavier, more damage prone, and allows less air circulation than a modern negative footprint rail. Start A Program Remotely more. In addition, the clever grooved barrel nut system of the M2. First, it is made from steel tubing, and consequently the finished products are slightly out of round, hampering rigidity and rail alignment. This rail rigidity is important for night operations when using a rail mounted laser aiming device A 1. MOA shift in the rails position results in a target miss at 2. Also, the steel construction of the nut and heavy barrel of the M2. Further, the steel barrel nut wears the threads on the receiver relatively quickly as barrels are taken on and off for maintenance, meaning receivers must be replaced more regularly.