The M40 rifle might be the most recognizable of all American sniper rifles. Its birth coincided with a need for a precision instrument in the steamy jungles of Vietnam, and its legacy was built by those who relied on its performance. Its accuracy, reliability, and endurance have given rise to a generation of precision rifles that ultimately pay homage to its design.
While a whole book could be dedicated to studying the rifle’s impact and history, this article seeks to provide context and understanding of the M40 rifle’s origin in Vietnam.
Cold War Heats Up
The United States entered Vietnam to preserve democracy and fend off a growing communist threat — a common theme of the Cold War-era. However, this was a new kind of war for the United States, fought against an unconventional enemy.
Unlike the Korean War, which was largely fought against a conventional force, the war in Vietnam was unconventional. New military stratagems, including a rapidly growing intelligence and special operations apparatus, were emerging. Among these were expanded use of specially trained hunters: snipers.
This certainly wasn’t the first time in United States history that snipers were used. Marksmen of various kinds have been used since the Revolutionary War. However, they were never a permanent peacetime unit like those we see today. They were temporary, which meant that a consistent curriculum and armaments were not properly maintained. But as warfare changed, so did the role of the sniper, or rather, the need for one.
That brings us to the M40 sniper rifle and its place in history. Early in the Vietnam War, military leaders and strategists quickly realized the need for snipers. The dense jungles and the unconventional opponent proved difficult for a standard military. The North Vietnamese Army (NVA) knew this and, early in the war, exploited it. The NVA benefited from using the Soviet Union’s WWII sniper training doctrine and rifles to engage American troops from a distance.
American military brass soon realized they needed a counter to the NVA threat with specially trained soldiers to carry out very specific missions. These missions involved gathering intelligence, disrupting supply chains, protecting military units, and, in some cases, eliminating high-value targets.
While sniper-specific training at this time was rudimentary and ad hoc, the rifle situation was worse. Early sniper units relied on rifles and training developed during World War II. A new rifle and training regime were needed.
The training came first — largely due to the efforts of Maj. Jim Land. If that name is familiar, you’ve probably read Marine Sniper: 93 Confirmed Kills by Charles Henderson. This book depicts the life and actions of Gunnery Sgt. Carlos Hathcock.
Maj. Land was responsible for shifting the Marine Corps’ emphasis on sniping. He established the first organized sniper training school in 1961 in Hawaii. This laid the groundwork for additional in-country sniper schools used by the 1st and 3rd Marine Divisions. Ultimately, this was the predecessor to modern-day sniper instruction.
What About a Sniper Rifle?
Leftover rifles from World War II and the Korean War, including the M1C/M1D Garand and modified 1903A4 Springfield rifles, no longer met the United States Marine Corps’ grueling demands. By then, these rifles were practically historic artifacts.
Early in the war, sniper units drew on the inventories of marksmanship units for Model 70 target rifles. While the M70 was an excellent rifle, its .30-06 chambering and inherent engineering changes made it a logistical nightmare. There were three different Model 70 variants were in use, and parts interchangeability was a major issue. However, the rifle had its supporters including the aforementioned Gunnery Sgt. Hathcock.
In 1965, Marine Headquarters instructed the Quantico Marine Schools Weapons Training Battalion to issue verbal orders to the Marksmanship Training Unit to procure a rifle, telescopic sight, and mount suitable for use by snipers.
Soon after the initial order, the officer in charge of the Marksmanship Training Unit responded on February 9, 1966, to the Marine Corps Commandant, stating, “The indicated urgency for an early recommendation dictated that evaluation be limited to presently available commercial items.” A military rifle hadn’t yet been developed in the United States for use as a sniper rifle. Thankfully, the United States has a rich tradition of rifle building.
In the same response, a subsection titled “Self-Imposed Assumptions” listed several rifle requirements. “…the selected sniper system to use the standard 7.62mm NATO ammunition and be simple, sturdy, and explainable with a minimum amount of instruction.” Five rifles were tested, including the Winchester Model 70, the Harrington and Richardson Ultra-Rifle, and three Remington models. In addition, seven telescopic sights were tested.
The Model 70 was quickly disqualified because it was chambered in .30-06. The Ultra-Rifle was also discarded because its construction used components from several manufacturers. Likewise, the Remington Model 600 and 700 ADL were deemed “too light” for military sniping operations. Only the 40X passed all requirements and testing.
Along with rifle and optic requirements, the MTU letter’s final paragraph added, “Thus, along with the M40 sniper rifles, came special ammunition manufactured for the marksmen’s use on the range and the battlefield.” This line presents a form of unification within a specific weapons system.
For the Marines and the rest of the U.S. Military, this was the first time a precision rifle was viewed as a system. Rifle, optic, case, ammunition, sling, and all ancillary gear and components were streamlined into one system. (As for the ammo, this was the birth of the famed M118 7.62X51mm Match ammo.)
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The Marines contracted for an initial batch of 700 M40 rifles (though over 900 were delivered). They were shipped in plastic cases designed to hold the entire system. An important part of that early sniper system was the Redfield Accu-Range scope. Its 3-9X magnification range and compact size were state-of-the-art in 1966. A distinctive feature was its ranging reticle, which could range targets out to 600 yards. The package was held together by mounts that were near facsimiles of those used on the 1903A4 Springfield rifle.
One important distinction between the prototype and the production M40 rifle was the inclusion of a clip-slotted bridge on the 40-X receiver. The slot allowed quick loading of ammunition via stripper clips. All production model M40 rifles were built on the standard 700 short-action, with no slot for stripper clips.
M40 Rifle Evolves in Vietnam
The M40 proved to be an accurate rifle. It was quickly deployed in the harsh combat in Vietnam, and Marine Snipers were able to confidently engage the NVA and VC (Viet Cong). However, Vietnam was a bit different than Quantico, VA.
Early rifles shot well but weren’t necessarily ideal for humid jungles. The wooden stock was the culprit behind questionable serviceability. Vietnam is tropical; it rains a lot. Wood, such as the stock of an M40 rifle, reacts to moisture. High humidity causes the wooden stock to expand and contract. Conversely, swollen wood creates pressure points along the barrel, affecting accuracy.
The only solution is to remove the barreled action from the stock and sand down the high spots. An annoyance, to say the least. Harsh conditions further sidelined many of the original contracted rifles. Rust, cracked optics, broken triggers, and a lack of parts led to the rifle’s evolution into the M40A1 in 1973.
Modifications to the M40 included welding the recoil lug and internal magazine box to create a solid one-piece body. Next, the original aluminum trigger guard and magazine floorplate were replaced with a modified steel version borrowed from Model 70 rifles. The chrome-moly barrels, which were prone to rust, were replaced with Atkinson stainless-steel tubes finished in black oxide. Finally, the dated wood stock was replaced with a fiberglass one from McMillan and had an integral camouflage finish.
While these modifications were significant upgrades over its predecessor, the gun weighed 12 lbs., 3 lbs. heavier than the M40. Fielded from the 1970s into the 2000s, the M40A1 is the Marine Corps’ longest-serving sniper rifle.
The Legacy of the M40 Sniper Rifle
The Vietnam War marked a change in warfare, or rather, how warfare was conducted. Unconventional combat and the soldiers skilled in this action, such as snipers, rebalanced the playing field. Their surgical use laid the groundwork for future warfighters. As a result, the famed M40 they used is often the sniper rifle to which all others are compared.
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