The Army Needs To Replace the M4 Carbine. What Would Make the Ultimate Rifle?

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.

byKyle Mizokami

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 Sixties, 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.

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.