A ‘Special’ Kind of Ammunition
What made the M2 such an impressive weapon was the bullets it fired. From the very beginning, the .50-caliber rounds designed for the M2 were something special. The term “caliber” in the context of small arms means the diameter of the bore, measured in decimal fractions of an inch. So, in metric terms the M2 is designated as a 12.7mm weapon. Initially, the specifications for the M2 “ball” round were for a simple solid shot, little different in makeup from the .30-caliber round of the M1917A1. For the development of the ball round, the army contracted to Winchester, which began by working from their existing 16-gauge brass shotgun shells. Eventually, work on the .50-caliber round was transferred to the Frankford Arsenal where a number of different designs were tried. Eventually, a modified .30-caliber 30-06 design became the M1924/M2 machine- gun cartridge.
The basic shape of the M2 ball round is almost aerodynamically perfect (“ball” here does not mean spherical but solid, that is, not having a cavity into which chemicals are placed for tracer or explosive use). The form of the .50-caliber round has a slight taper at the bottom, which has the effect of reducing drag and maintaining stability. So perfect is the shape, in fact, that a generation later, when engineers at Bell Aircraft were deciding on the shape for the X-1 supersonic research aircraft that would break Mach 1, they based it on the .50-caliber round of the M2. As an added bonus, the .50- caliber round had enough volume and weight that it could support fillers like a base tracer or an incendiary core, and could be made of various materials including tungsten for armor piercing. Even today, ordnance engineers look in awe and wonder at the vision and genius of the .50-caliber round, designed at a time when slide rules, adding machines, and blackboards were the high-tech tools of the gunmaking trade.
“Ma Duce” first entered service with the U.S. Army in 1919, too late for service in World War I. Nevertheless, the M2 became an instant hit wherever it was installed or deployed, for both its amazing hitting power and range and its genuine simplicity of operation. Much of this derived from the simple recoil operation of the weapon, a signature John Browning design feature. “Recoil operated” means that it uses an ingenious arrangement of levers, cams, and springs to capture part of the powerful recoil energy of the fired cartridge, uses it to extract and eject the spent cartridge case, then to feed the next round, load and fire it.
An Accurate Weapon That Can Hit Targets Over a Mile Away
This cycle repeats as long as the gunner holds down the “V”-shaped trigger located between the two handgrips at the rear of the gun. Release the trigger and a latch secures the mechanism in the “open bolt” position, ready to fire again. In fact, when firing the M2 on full automatic (there are also single-shot and semiautomatic modes), the sensation to the gunner is a lot like riding a classic Harley-Davidson “Hog” motorcycle: The power is something you feel as much as hear and see!
Nevertheless, the M2 is not always an “easy” weapon to possess and maintain. While rugged and well built, it requires a fair amount of maintenance and cleaning, especially in the adjustment of the “headspace” between the rear of the cartridge and the bolt. In addition, the weight and fairly high recoil of the M2 require a sturdy and stiff mount for effective shooting, mandating either the previously mentioned heavy tripod or a secure “pintle” mount tied to the structure of a ship, aircraft, or vehicle.
The payoff, though, is a weapon that can hit targets with ease over a mile away, with an accuracy that is often surprising. During the Vietnam War, the legendary Marine sniper Sergeant Carlos Hathcock obtained many of his 93 “kills” at ranges up to 2,500 yards with standard M2 machine guns and a special telescopic sight he carried in his gear. So effective was the combination that, 20 years later, a Tennessee gun designer named Ronnie Barrett would design a lightweight .50-caliber sniper rifle firing the M2 ball round that would become a standard weapon for the U.S. Army, Navy, and Marine Corps.
The 1920s and 1930s saw the gradual acceptance of the M2 into every service in the U.S. military, including the Coast Guard. By the start of World War II, the M2 was the standard weapon for U.S. fighter and bomber aircraft, tanks and scout cars, and the primary antiaircraft weapon for naval vessels. As might be imagined, though, the needs of a two-ocean war made for a voracious demand for the M2, which only grew as the conflict went on. For example, B-17 and B-24 heavy bombers each had a dozen M2s as their defensive armament, while six of the .50-caliber weapons became standard for the F-6F Hellcat, F-4U Corsair, and P-51 Mustang fighters. Millions of the .50-caliber weapons were produced and used in every theater of the war. By the end of the conflict, the M2 had become the most produced machine gun of all time, with millions in service around the world.
Even more impressive were the myriad rounds produced for the M2, numbering into the billions. By the start of World War II, the basic M2 ball round (later improved into the M33 configuration) had grown into an entire family of ammunition (see Sidebar).
Nine Decades of Continuous Service
A “normal” mix of rounds for most applications would include two rounds of TP/ball, two of API, and one of tracer in five-round groups, providing a good range of end effects. The ammunition is assembled into belts with reusable spring clips called “disintegrating links” because they are stripped off by the gun’s feeder mechanism. Using the ammunition shown in the sidebar, the theoretical maximum range for the M2 is 4.2 miles, and has actually been used for indirect fire at high angles of elevation to create a “fire beaten zone” on the far side of a hill. The practical maximum range for aimed direct fire is about one mile.
At shorter ranges, the effects are truly amazing. With a rate of fire of between 400 and 550 rounds a minute, .50-caliber rounds from the M2 can literally shred drywall or wooden buildings, or even unarmored vehicles. At favorable angles and ranges it can penetrate the top, side, or rear plating of armored vehicles and aircraft like personnel carriers, infantry fighting vehicles, or attack/scout helicopters. This makes the M2 a very dangerous thing to have in your bag of military tricks, and is why the .50-caliber has remained the love of soldiers, sailors, and Marines in every military force that fields it.
As the M2 enters its ninth decade of continuous service and production, one might think that it is ready for a well-deserved retirement and replacement. However, that assumption is wrong. The basic virtues of the M2 still make it the choice of military professionals all over the world more than 80 years after its introduction to service. The threat of naval terrorism has meant that every U.S. naval vessel now has pintel mounts for a pair of M2s. The guns are still found in heavy weapons units of every Army and Marine Corps formation in service. Long after some guided missiles and nuclear weapons have gone to the boneyard, “Ma Duce” continues to soldier on into a new century, made relevant again by a new era of conventional warfare.
Although the gun never wears out, the United States continues to maintain the tooling and industrial base to produce it. New-production M2s still are being delivered today, the current contractor for the U.S. military being Saco Defense, Inc. (recently acquired by General Dynamics of Maine). Its unit cost is $14,400, cost-effective considering its range, lethality, durability, and simplicity.
As the M2 soldiers on, the fact is that the last M2 gunner has probably not yet been born. This is an almost ageless weapon, whose utility has gone through more wars, engagements, and incidents than historians could probably tally. Nevertheless, “Ma Duce” is still out there, with the kind of reputation and affection usually associated with a new sports car or bass boat by the gunners who man them. It is fitting that she will probably outlive them, too.
This article first appeared at the Warfare History Network.