M27 IAR (including M38 SPR)

HK 's sample gun for the US Marine Corps' IAR competition is the HK416 with a 16.5-inch (about 420mm) barrel. Unlike other IAR sample guns, HK IAR does not have other special improvements (such as two firing modes like FN IAR , or a large heat sink like Colt IAR ). However, HK IAR is the lightest among all competing models, weighing 7.9 pounds (about 3.6kg) when empty, and the operation is the same as M16. Ordinary soldiers do not need special training to master it, because HK simply directly took out one of the carbine models of HK416 to participate in the bidding. According to the Marine Corps Times on December 2, 2009 , HK IAR won the bid in this project. In May 2010, HK IAR was officially designated as M27 and has begun to be delivered to troops for trial.

The Marine Corps does not require the IAR to have a quick barrel replacement function. The US military has always believed that machine guns must be able to quickly replace barrels in order to cope with long-term sustained firepower. Obviously, for the IAR , the Marine Corps does not attach importance to its sustained firepower, but rather to its mobility. Interestingly, based on China's experience in the self-defense counterattack against Vietnam, the squad light machine gun is closer to the enemy than other fire support weapons, so it is often the target of the enemy's special attention. The squad light machine gun often has to move the firing position after firing a few bursts at one position. Therefore, in actual combat, the chance of the squad light machine gun firing until the barrel turns red is not great, so China does not need to quickly replace the barrel of the squad light machine gun, but instead emphasizes lightness. Obviously, the IAR is also positioned to provide fire support at close range, which can be seen from the fact that all the sample guns used carbine-length barrels during the bidding. Moreover , according to the plan in 2009, this batch of IARs was not to completely replace the M249 , but it was planned to replace one of the three M249s in the Marine Corps infantry squad with two IARs , so equipping the Marine Corps infantry squad with IARs would not reduce the firepower of the Marine Corps infantry squad.

The disassembled M27 has a heavy barrel compared to the ordinary M4 "pencil barrel", but in fact, the standard barrel of the HK416 is this heavy barrel.

Another disassembled HK416. It has two bayonet catches. It may be an early batch of HK416 that was assembled directly from the gas hoop that came with the 14.5-inch barrel.

The plan in 2009 was to replace the 3 M249s in the infantry squad with 2 M249s + 2 IARs . In December 2010, a total of 5 battalions were equipped with 450 M27s for testing. Among them, the 3rd, 4th, 9th and 1st Battalions of the 25th Marine Regiment of the 3rd Marine Division replaced all the M249s in the squad with M27s, while the 1st Light Reconnaissance Battalion (Armored Reconnaissance Battalion) only replaced half of the M249s. The different configuration methods are probably for various forms of testing to confirm whether to officially equip the M27.

The 3rd Marine Division entered Afghanistan in April 2011 with 84 M27s . The initial news was that these "machine gunners" did not like the M27 , but as time went on, more people began to appreciate it. Because the M27 is very light, it is a significant advantage for long-term marching operations. Some M27 shooters said that the gun can accurately shoot at targets 800 meters away, and the enemy cannot tell who is the machine gunner, and it is easy to move positions; usually accurate shooting is carried out on long-distance targets, and fire suppression is carried out on targets within 200 meters. So some M27 shooters simply switched to DMR shooters. In addition, the gun has the advantage of simpler maintenance. Therefore, the Marine Corps tried to get more budget to develop IAR into a multi-purpose weapon that serves as both a light machine gun and a DMR rifle.

However, the troops who tried it on the front line in Afghanistan also believed that although the M27 had the advantages of high accuracy and high reliability, they complained that the magazine capacity was too low and the firepower sustainability was too low when used as fire support. Because so far, the magazines equipped with the M27 are all 30-round standard magazines. When the IAR project was announced, it was also mentioned that the Marine Corps was testing a 150 -round CL-MAG drum produced by Armatac Industries , but the test found that the CL-MAG drum was prone to malfunction at high and low temperatures, and it was also prone to malfunction in harsh environments such as jungles and deserts, so it was finally decided not to equip this large-capacity ammunition supply, resulting in soldiers using M27 still using 30 -round standard magazines. According to the amount of ammunition carried by a squad machine gun shooter, it is stipulated that an M27 shooter needs to carry 21 30-round magazines. As a result, many shooters are lazy and do not actually carry so many magazines. It is said that the Marine Corps also tested SureFire's SF-MAG5-100 4-row magazine , but found that the magazine base was easy to fall off, and the magazine was too long and would hit the ground when shooting in a prone position, so SureFire's 4-row magazine was also abandoned.

M27 Accessories

ACOG TA11 SDO-CP graticule, with the lower part taking into account the terminal spin shift

In addition, the Marine Corps' M27s are all equipped with a standard 3.5x SDO (Squad Day Optic) scope, which is the model of Trijicon ACOG suitable for squad machine guns. The US military standard equipment number is SU-258/PVQ.

HK IAR exhibited at SHOT SHOW 2010

The 150-round CL-MAG that the Marines tested during the IAR competition

After being equipped with the M27, the Marine Corps may have tested the PMAG D-60 60-round drum magazine from MAGPUL.

The Marines first equipped with the M27

At the end of 2010, the 1st Battalion, 3rd Marine Regiment, stationed in Hawaii, received the M27

The M27 IAR undergoing combat testing in Afghanistan in 2011

The M27 during trials in Afghanistan in 2012

M27 used by MEU in Afghanistan in 2013

M27 IAR with OKC-3S bayonet

M27 IAR with blank cartridge recoil assist device installed on muzzle

M27 IAR in single shot mode

A Marine firing a burst of fire from his M27 IAR

Installing KAC QD silencer on M27 IAR

Installing EOTECH holographic sight on M27

M38 SPR

As mentioned earlier, the U.S. Marine Corps intends to develop the M27 into a DMR weapon. In 2016, they sought to order another 15,000 M27 IARs and convert some of them into M38 DMRs. The Marine Corps tested 9 M27 IARs converted into DMRs at the Quantico Marine Corps Base in Virginia, each firing 2,700 rounds of ammunition. The basic configuration named M38 SPR (Special Purpose Rifle) by the Marine Corps was finally determined. In fact, although the model names are different, there is no difference between the M38 SPR and the M27 IAR in the gun body, and other accessories are similar. The only difference is that a Leupold Mark 4 2.5-8x36mm variable magnification scope is replaced. The reason for choosing this scope is simply because there is a ready-made inventory in the warehouse. Originally, these scopes were used for old SDM-R or Mk12 SPR . If a silencer is required, it is equipped with a KAC QD silencer. The first batch of M38 SPRs were put into use in December 2017. A total of 864 M38 SPRs were converted as squad DMRs to deal with targets 600 meters away.

The M38 SPR being tested at Quantico in 2016

The final M38 SPR configuration is just the M27 IAR with a different scope.

When testing the M38 SPR, I tried the configuration of a short barrel with an OSS HX suppressor, but ultimately did not choose this configuration.

M38 SPR delivered to the troops

M27 RWK

The M27 Reconnaissance Weapons Kit is actually a CQB version that replaces the M27's 16.5-inch barrel with an 11-inch (about 279mm) barrel. It is said that the purchase order came from the Marine Corps' reconnaissance unit, but they did not order the barrel to install it themselves, but ordered a complete HK416A5 upper receiver including the barrel for replacement. This is because the M27's handguard is longer than the standard handguard of the HK416. If an 11-inch barrel is used, a shorter standard handguard is required. Since the A5 upper receiver was purchased, some of the improved features on the A5 are also included in this M27 RWK, such as the improved adjustable gas hoop. Among them, the 2nd Reconnaissance Battalion of the 2nd Marine Division began to use this M27 RWK for the first time in May 2021, and then this short-barreled M27 may also be equipped with other reconnaissance units of the US Marine Corps, including the Expeditionary Force's direct reconnaissance company (Force Recon). The reason for purchasing the A5 upper receiver is that the Marine Corps' reconnaissance unit does not have a short rifle. They cannot just report and get a short rifle like SOCOM's MARSOC. To facilitate procurement, the Marine Corps directly purchased the A5 upper receiver. After all, the upper receiver is considered an accessory, and the lower receiver is the gun. According to the U.S. military's equipment procurement system, it is easier to buy accessories than guns. (Added by @ Zenith_Concepts at B Station )