These are the differences between the M40 and M24 sniper rifles

In the U.S. military, the majority of sniping work is done by the Army and the Marine Corps. These forces use very similar rifles: the Marine Corps fields the M40, and the Army the M24.

Both rifles are Remington 700s at their core. Each is designed to provide a sniper with a long-range tool for accurately eliminating the enemy. They are both bolt-action rifles, and when adopted, both came in the standard 7.62x51mm NATO cartridge, and when put side-to-side they’re hard to tell apart.

But they aren’t the same weapon.

The M40 and M24 – A brief history

Unlike the standard infantry rifle or handgun, the services independently sought sniper rifles but arrived at the same general answer to their problem.

The beginnings of the M40

When the Marine Corps landed in Vietnam, they brought with them a mixture of sniping rifles. The Marine Corps was never one for the latest and greatest equipment, so early in the war, they carried a mixture of M1C and M1D versions of the M1 Garand rifle, as well as old M1903A4 rifles. Later in the war, they got the Winchester Model 70, which was used by iconic sniper Carlos Hathcock.

This mixture created a logistical chaos within the Marine Corps sniper communities. Optics, ammo, optics mounts, and even slings could be different depending on the rifle. So the Marines needed to standardize on a rifle platform. In 1966 they ordered 700 model Remington 700s and dubbed them the M40.

The beginnings of the M24

The U.S. Army fielded the M21 as a sniping weapon in Vietnam. The M21 was an accurized and optically enhanced M14 rifle. It was a semi-auto, magazine-fed rifle that used a 3-9X variable Redfield scope or a Starlight night vision optic. Yet, its 20-round magazine protruded from the rifle’s bottom significantly, making it harder to assume a low prone for a stable and well-hidden position.

The M14 series of rifles was plagued with issues from the start. According to a Ft. Benning publication, the M21 could not be “maintained under field conditions, and its inflexible design [made] it highly susceptible to malfunctions.” The rifle’s wooden stock would also warp when subjected to the jungle’s humid environment.

So, the Army needed a rifle made from the ground up for sniping and in 1988 it adopted the Remington 700 as the M24.

Where the differences come in

The main difference between the M40 and M24 is their action. The M40 series used by the Marine Corps utilized what is known as a short action, which uses cartridges with an overall length of 2.75 inches, like the famed 7.62 NATO round, which the Marines used on the M40 from the start.

On the other hand, the M24 uses the Remington long action that can use cartridges as long as 3.6 inches. The Army was originally going to use the .30-06 cartridge used by the M24, and specifically, they wanted to use the M72 Match grade rounds. However, it was found that there was an insufficient quantity of M72 match rounds, so the Army also moved to the 7.62 NATO cartridge.

The downsides of a long-action cartridge, like the M24’s, are few. The bolt travel is longer, and the gun is slightly longer and heavier. However, using the long action allowed the Army to upgrade the system and use larger, more powerful cartridges.

The two rifles have several minor differences. The Marines used a 25-inch barrel and the Army used a 24-inch one. The earliest M40s wore wood stocks, but the Marine Corps recognized the problem and ditched them for fiberglass stocks. The Army avoided the Marine Corps issue by using a nonwood stock from the very beginning.

The Modern M40 and M24

(U.S. Marine Corps photo by Sgt. Matthew Teutsch)

Over time the differences between the two platforms increased significantly. The Army went on to evolve the M24 platform into the M2010 Enhanced Sniper rifle, which maintains the Remington long action design and uses the much more powerful .300 Winchester Magnum cartridge. The weapon uses a chassis system that includes a folding stock and plenty of rails to attach numerous accessories.

At the same time, the Marines’ M40 series developed through several stages, finally landing on the M40A6. The rifle still uses the 7.62 NATO cartridge and now sits into a chassis system with rails to accommodate day and night optics and a side folding stock.

It’s interesting to see that both the Army and Marine Corps eventually drifted toward the same path of modernization for their respective platforms. Even more interesting is that both military services have decided to drop their rifles to adopt variations of the Barrett MRAD.

The Remington 700 has served American forces as the M40 and M24 for decades now, and maybe it’s time the old warfighter retires.

Feature Image: Lance Corporal Walter Pereira, Scout Sniper, Scout Sniper Platoon, Weapons Company, 1st Battalion, 4th Marines, 13th Marine Expeditionary Unit rehearses standing, sitting, and kneeling drills with an M40 A5 rifle mounted on a tripod Nov. 1, 2013 prior to attending a live fire range. (USMC photo by Gunnery Sgt. Matt. Orr/Released)