What Would The Army's Ultimate M4 Carbine Replacement Look Like?

Military Tech

The U.S. Army is looking for a new weapon for infantry troops. After a half-century of using the M16/M4 carbine series of weapons, the Army is looking for a weapon with increased range and lethality to deal with future threats. Although the search is still in its early stages, looking at the threats and the current state of small arms technology we can get an idea of what the service might shoot for — figuratively speaking — in a new soldier weapon.

The current U.S. Army weapon that the service eventually seeks to replace is the M4 carbine. An evolution of the original M16 introduced in the mid-1960s, the M4 is more compact and more reliable than its ancestor. Thanks to improved ammunition the M4 is able to penetrate lightweight body armor, and the use of optics allows soldiers to place rounds on target more accurately at longer ranges than ever before.

All of that having been said, the M4’s basic design precludes important upgrades. The use of a direct impingement operating system, although simple and effective, requires more frequent cleaning and alternatives exist. The 5.56-millimeter round, although lightweight and logistically appealing, is reaching a dead end performance-wise and a good argument exists that it needs replacing.

Now, let’s look at the threat and operating environment. Unlike many ground forces, the U.S. Army must be ready to fight literally anywhere and against anyone on the planet. Soldiers must be capable of engaging enemy troops at short ranges in cities while at the same time being capable of long-range fire against enemies in open terrain. The weapon must be capable of controlled fully automatic fire in close quarters battle while at the same time having the energy to engage targets at long ranges. The cartridge the weapon fires must be capable of penetrating modern, advanced body armor while still tumbling shortly after entering the human body, creating lethal wound cavities.

A U.S. Army paratrooper assigned to the 82nd Airborne Division fires an M4 Carbine during the last day of the Small Arms Competition as part of All American Week XXIX at Fort Bragg, North Carolina, May 23, 2018.U.S. Army/ Sgt. Michelle U. Blesam

Fulfilling all of these requirements, some of which are inherently contradictory is no easy task, and it’s easy to see why a conservative organization like the U.S. Army simply decided to upgrade the existing basic design over and over again. It’s difficult enough to meet this challenge, let alone demand a weapon with ten times the performance of the existing M4. Instead, we’ll envision a weapon that is a cost-effective improvement over the M4 with the capability to further grow down the road.

For our weapon, which we’ll call the M5, we’re going to switch to a familiar, but internally different platform: the Heckler and Koch 416 assault rifle. The HK 416 is externally nearly identical to the M4 carbine, aside from some cosmetic changes, but internally uses a gas-piston operating system that requires less frequent cleaning. The similarities between the two platforms will make transitioning to the new carbine for existing troops easier.

The modular system of the M5, which breaks down into upper and lower receivers, will allow the Army to make future changes—such as caliber changes or trigger group improvements--possible without buying a completely new weapon. This will make upgrades easier to implement in the future.

Another key change: switching to a new cartridge. The M5 will be chambered in 6.5-millimeter Grendel. The 6.5 Grendel round offers improved range and lethality over the existing 5.55-millimeter round without utilizing fundamentally different technology (such as cased telescope cartridges, polymer cases, or fully caseless ammunition). The M5 would use the same 14.5-inch long barrel as the existing M4 carbine, ensuring that the weapon is manageable in the enclosed spaces of a truck, Stryker armored vehicle, or M2 Bradley infantry fighting vehicle.

The Army would purchase the M5 stock without optics or aiming devices, an a la carte solution that recognizes a permanently attached optic--such as the optic on the German Army’s Heckler and Koch G36 assault rifle --is unlikely to be ideal under every circumstance. Instead, the M5 would feature M1913 Picatinny rails at the three, six, nine and twelve o’clock positions outside the barrel and along the top of the upper receiver. This would allow the Army to change the optic depending on the circumstance and make future upgrades easier.

One of the best things about our weapon design is that it’s actually the M4 carbine! The U.S. Army could have this new carbine by replacing the upper receiver on existing M4s with an HK 416 upper receiver chambered in 6.5-millimeter Grendel. This recycles at least half of the carbine, saving acquisition costs over buying an entirely new weapon. The M5 externally would look almost identical to the M4.

There are a few downsides to the new weapon. A 6.5-millimeter Grendel weapon would require new ammunition magazines and vast new stocks of 6.5-millimeter ammunition. Furthermore, the magazines would carry 24 rounds of ammunition, six rounds less than a 5.56-millimeter ammunition magazine. That’s an inherent tradeoff of having a slightly larger, more powerful round. The new round would also be a non-standard NATO round and incompatible with rifles and carbines fielded by our allies--most of whom show no intention of migrating away from the 5.56 cartridge.

In choosing a new carbine, the U.S. Army must navigate a maze of requirements, prioritizing them and likely leave some of them unfulfilled in order to field a rifle. It must also recognize that against the backdrop of more expensive modernization efforts, such as the effort to produce next-generation helicopters and infantry fighting vehicles, procurement budgets in the 2020s and 2030s will be tight and there will be a temptation to “make do” with the M4. The new weapon must be as budget friendly as possible while still offering enough improved performance to justify the expense. The “M5” is such a weapon, offering improved lethality and range without breaking the bank.

This story originally appeared on The National Interest

Read more from The National Interest:


(Associated Press/Tom Williams)

Ronny Jackson, the former White House physician and retired Navy rear admiral who had a short run as the nominee for the Department of Veterans Affairs in 2018, now plans to run for a seat in Congress.

Read More Show Less

The Pentagon will implement an "operational pause" on the training of foreign students inside the United States as the military undergoes a review of screening procedures, according to senior defense officials.

Read More Show Less
In this Nov 24, 2009, file photo, a University of Phoenix billboard is shown in Chandler, Ariz. The University of Phoenix for-profit college and its parent company will pay $50 million and cancel $141 million in student debt to settle allegations of deceptive advertisement brought by the Federal Trade Commission. (AP Photo/Matt York)

WASHINGTON (Reuters) - The University of Phoenix, which is owned by Apollo Education Group, has agreed to pay $191 million to settle charges that it falsely advertised close ties with major U.S. companies that could lead to jobs for students, the Federal Trade Commission said on Tuesday.

The University of Phoenix will pay $50 million to the FTC to return to consumers and cancel $141 million in student debt.

Some of the advertisements targeted military and Hispanic students, the FTC said.

Read More Show Less
Shane Reynolds, UCF Research Associate demonstrates an AR/VR system to train soldiers and Marines on how to improve their ability to detect improvised explosive devices. (Orlando Sentinel/Ricardo Ramirez Buxeda)

As UCF research associate Shane Reynolds guides his avatar over a virtual minefield using his iPad, small beeps and whistles reveal the location of the scourge of the modern war zone: Improvised Explosive Devices, or IEDs. He must take his time to sweep every last inch of the playing field to make sure his character doesn't miss any of the often-deadly bombs.

Despite his slow pace, Reynolds makes a small misstep and with a kaboom! a bomb blows up his player, graphically scattering body parts.

Read More Show Less
US Navy

The Navy has posthumously awarded aviator and aircrewman wings to three sailors killed in last week's shooting at Naval Air Station Pensacola.

"The selfless acts of heroism displayed by these young Sailors the morning of Dec. 6 are nothing short of incredible," Chief of Naval Air Training Rear Adm. Daniel Dwyer said in a statement.

Read More Show Less