One Cartridge, Two Roles?

 I'm on the SOFREP mailing list and received an email 5 or 6 days ago with the subject: "One Cartridge, Two Roles: The Logic Behind the M7 and M250." The M7 is the Army's new automatic rifle and the M250 is a belt fed machine gun, both using the 6.8x51 cartridge. The email touts this as a boon:

    ... One cartridge feeding both the rifleman and the automatic rifleman means the squad is speaking the same ballistic language when the fight stretches across terrain. The rifle is no longer living in one performance envelope while the gunner works in another. Effects downrange start to align.

    That kind of commonality simplifies more than logistics. It stabilizes planning. When ammunition feeds both roles from the same family, resupply becomes less fragile, and leaders spend less time managing caliber mismatches under pressure. The squad carries one core solution instead of juggling two separate ones.

    There are tradeoffs. A higher-energy cartridge brings more recoil and more heat. It demands discipline and training. But it also gives the automatic rifle greater reach and authority while letting the rifleman stay relevant at distances where legacy systems begin to fall off. That overlap is the point.  

While simplifying logistics is laudable, I'm not convinced that replacing the multitude of personal weapons used in WWII and Korea with a single heavy rifle, the M14 (which was quickly replaced by the M16) was all that beneficial, and yet that is what we are doing all over again. And I'm not convinced that the M7 and M250 will have the same "performance window"--the belt fed machine gun will always be able to operate at longer distances than the rifle if for no other reason than that the machine gunner can drop bullets onto a beaten zone at far greater distances than a rifleman can deliver accurate shots. Besides which, Afghanistan aside, the trend over the past 60 years has been more and more fighting in built up environments. So I have to ask whether the M7 is trying to bet against the trend.

    I have no problem with the M7 as a DMR or even as a "mountain rifle"--I've always thought that it made sense for troops in certain environments to have rifles capable of longer ranges--but not as a general issue weapon. Moreover, I suspect that something like the 6mm ARC would have met most of the requirements that the Army wanted with the 6.8x51, but could have been done with a simple change of the upper and magazine rather than a whole new rifle. 

    Even the increased lethality argument is suspect. I'm not saying that the lethality of an individual round might not be more, but that compared to the magazine capacity, the lethality is not necessarily increased. I can best explain what I mean by an illustration from an article I recently came across on the .458 SOCOM round.  Discussing the cartridge's backstory, the article states:

    ... The story goes that Marty ter Weeme, founder of Teppo Jutsu LLC, and a member of the U.S. Special Operations world were discussing what they considered the lackluster performance of the 5.56 NATO M855 round during a battle between members of Task Force Ranger and Somali militants. Reportedly, multiple hits with the 5.56 were required to neutralize adversaries. This led to the conception of a large-caliber cartridge compatible with the AR-15/M16/M4 platform in .458-caliber. 

It had impressive ballistics--at least for CQB. But the downside? "With the new follower, a 30-round 5.56 NATO magazine could [only] hold 10 rounds of .458 SOCOM," and the increased recoil made it more difficult to put multiple rounds on target. Also: "A Soldier armed with a 5.56 NATO-chambered AR, carrying 10 pounds of ammo, could carry nearly 400 rounds, while a Soldier armed with a .458 SOCOM-chambered carbine could only carry about 140 rounds." So, even if it took three hits from a 5.56 to put down an enemy versus one shot from the .458, both used 1/10th of their magazine capacity to do so. And from that perspective, there would be no advantage to using the .458 round. 

    In any event, the Marines aren't buying it--"it" being the M7. The Defense-Blog reports that "U.S. Marine Corps rejects switch to M7 rifle." It relates:

    The United States Marine Corps has decided to retain the M27 Infantry Automatic Rifle for its close combat formations rather than adopt the Army’s M7 Next Generation Squad Weapon rifle, a Marine Corps spokesperson confirmed to Task & Purpose.

    “The Marine Corps will retain the M27 for our close combat formations as it best aligns with our unique service requirements, amphibious doctrinal employment of weapons, and distinct modernization priorities, while ensuring seamless interoperability across the Joint force and with coalition partners,” the spokesperson said in an email to the publication.

    The decision keeps the M27 as the Corps’ primary infantry rifle while the Army continues fielding the M7 and its companion M250 machine gun under the Next Generation Squad Weapon (NGSW) program. The Marine Corps indicated it will continue observing the Army’s program before making any future decisions.