WEAPONS OF THE WORLD WAR II GYRENE

M2 Heavy Barrel Machine Gun

Characteristics Caliber: .50 inch Weight (with tripod): 128 pounds Rate of fire: 450-550 rounds per minute Maximum effective range: 2,500 yards Method of loading: 105 round linked belts Sustained rate of fire: 40 rpm The M2HB was an air cooled, recoil operated, belt fed, heavy machine gun.

 

The .50 caliber machine gun was among the most versatile and powerful small arms used by American forces in the Second World War. It was unquestionably the finest heavy machine gun in the world and was used in aircraft, aboard ships, mounted on vehicles of all types, and by ground forces on tripods and anti-aircraft mounts. Almost 2,000,000 .50 caliber heavy machine guns were produced by American industry during the war years. Of this total, 347,524 were of the M2HB type.

Legendary firearms designer John M. Browning worked with the US Army Ordnance Department in developing a .50 caliber machine gun during the First World War. Using his proven .30 caliber M1917 machine gun as a guide, Browning cooperated with Colt's Patent Firearms Manufacturing Company to create a new weapon that was ready for testing the day after the war ended.

Continued testing and development of the .50 caliber machine gun moved on during the lean years after the Armistice. In 1933, the M2 .50 caliber water cooled machine gun was formally adopted in the anti-aircraft role. With a weight of over 500 pounds, this weapon was intended for employment in fixed sites such as air fields, base defenses and so on. The armed forces recognized that a flexible mount machine gun was necessary for ground forces, and that such a weapon needed a reliable air cooling system. The final version of this weapon was standardized as the M2HB Machine Gun in 1938. The designation "Heavy Barrel" indicated the the weapon had an improved barrel to compensate for lack of water cooling. The barrel length, originally 36 inches, was increased to 45 inches in 1938.

Anti-tank squad as depicted in Table of Organization D-3 (Weapons Company, Infantry Battalion.) In the D-series infantry battalion, the weapons company was assigned an Anti-tank and Anti-aircraft platoon equipped with two .50 caliber squads. USMC Photo

In the D-series table of organization, each infantry battalion was equipped with an anti-tank and anti-aircraft platoon. It was originally intended to issue these platoons with 20mm anti-aircraft guns, but these weapons were never procured to the Fleet Marine Force. Instead, as units were organized under the D-series, they were issued .50 M2HB machine guns. In addition to the machine guns in the battalion, each infantry regiment's heavy weapons company had three anti-tank and anti-aircraft platoons, each of which was assigned four M2HB machine guns.

Transportation of the heavy machine guns and ammunition presented a significant challenge in the foot-mobile Fleet Marine Force. In the infantry battalion, the AT and AA platoons were equipped with hand carts to transport weapons, equipment and ammunition. The regimental weapons company AT and AA platoons were each assigned a 1-ton 4 x 4 truck for this job. But the guns were extremely heavy and cumbersome, requiring immense effort to emplace under the harsh conditions of the Pacific battlefields.

When the First Marine Division landed on Guadalcanal in August 1942, it was organized under the D-series and the heavy machine guns were deployed everywhere in the Marine lines. Capt Ralph Kennedy, USMCR, was a heavy machine gun platoon leader on Guadalcanal, and recorded some of his thoughts in Leatherneck Magazine:

"In the first place, the gun had to be manhandled by the platoon the greater part of the time while it was originally intended to be transported by truck. Even if truck transportation had been available , it could have been used very little. Roads were few. There were no roads at all in many places near the front lines. Moving the guns by manpower and piece by piece was the only way they could be transported over much of this terrain."

Several types of ammunition were available, the most common of which were the M2 ball round, and the M1 tracer. These were assembled into belts at the factory with a mix of four ball rounds and one tracer round. The tracers burned out at about 1,600 yards. Also, an armor piercing round was available for this weapon. Early in the war, ammunition was issued in cloth belts. This was later supplemented, and finally replaced, by disintegrating metal-linked belts. Ammunition for the M2 was very heavy, weighing about 35 pounds for a can of 105 rounds. For example, the daily unit of fire on Guadalcanal for each gun was 26 cans with a total count of 2,730 rounds. The combined weight of this unit of fire for a single gun was 910 pounds.

1 February 1944 – A .50 machine gun squad of Weapons Co, 24th Marines, 4th Marine Division, sets up its gun during the assault on Namur Island in the Marshalls group. USMC Photo

The number of these weapons in the Marine infantry regiment varied through the war and is depicted in the table below.

.50 caliber M2HB employment in the Marine infantry regiment
TO	Number of weapons	Assigned to	Notes
D-series	18	Bns: 3 x 2 ea/Wpns Co: 12
E-series	16	Bns: 3 x 2 ea/Wpns Co: 10	AT/AA Plts deleted
F-series	10	Wpns Co: 10	Maintained at Co HQ
G-series	10	Wpns Co: 10	Maintained at Co HQ

As the table shows, the battalion and regimental anti-tank and anti-aircraft platoon was deleted from the inventory for the E-series and later tables of organization. After the deletion, these weapons were assigned to the battalion and regimental weapons company arms room, to be used as needed, and then returned to inventory.

Capt Kennedy made many good observation based upon his experience on Guadalcanal, Of the machine gun's deployment in combat, he wrote:

"The .50's were used on the main line of resistance more as a weapon against personnel than against enemy armored vehicles. Rather than let the guns remain in the rear and not be used at all, it was decided to put them on the front lines and use them against whatever targets presented themselves. There were but few approaches for tanks and armored vehicles and as these were adequately covered by 37mm guns and half-track 75's, the .50 caliber machine guns were not needed here. The air cooled .50 and the ground mount with which it is equipped could not be used as an anti-aircraft gun due to the restricted elevation while on the ground mount."

Several critical facts became clear based upon employment of .50 caliber machine guns in the Solomons. First was the supreme importance of weapons maintenance and methods to keep them firing under all conditions. Because the guns were relatively immobile, crews need to know how to build protective wire obstacles and sturdy firing emplacements. Lastly, crews had to be proficient at making range cards, and correctly clearing fields of fire.

One critical part of setting up the .50 caliber for firing was headspace and timing. This was a process of ensuring that the gun fired when all parts were set in the correct position. Each gun was issued with a headspace and timing gauge that the crew used each time the barrel was newly inserted or changed. If the gun was not headspaced and timed correctly, it could result in a catastrophic failure.

Infantry Marines advance through thick jungle supported by fire from the .50 caliber machine gun on an M4 medium tank. Still image from USMC combat camera film

Although the "ma deuce," as it was christened by Marines and soldiers, had its limitations, it was still an extremely potent weapon with a high degree of reliability and firepower. It was not only used by the infantry, but mounted on a wide variety of armored and soft-skin vehicles. Further, the tripod-mounted M2HB was used throughout the Marine division as a static defensive weapon. It was effective not only against aircraft in this role, but also against bunkers, sand bag emplacements, and other targets. The table below shows the varying number of M2HB machine guns in the Marine division during World War II.

.50 caliber M2 HB employment in the Marine division
Table of Organization	Number of weapons
D-series	360
E-series	343
F-series	161
G-series	162

During World War II, .50 calibers were manufactured by many firms in the United States. They included: AC Sparkplug, Frigidaire, Colt, Buffalo Arms, Brown-Lipe-Chapman (GM), Guide Lamp Division (GM), and Kelsey-Hayes. The .50 caliber is still in service in the 21st Century, after 80 years of service around the world. Although potential replacements have been developed from time to time over the years, none have matched the ma deuce for reliability and firepower. What is most astounding, some of the weapons built during the war are still in service to this day on the front lines of America's wars.

 

Peleliu – 1944. A 1st Marine Division 75mm Gun Motor Carriage during front line operations to reduce Japanese positions on the Umurbrogal. Two machine guns are mounted on the sides of the crew compartment, an M1919A4 on the left front, and an M2 HB on the right rear. USMC Photo

 

Peleliu – 1944. A 1st Marine Division amphibian tractor moves forward with the infantry into the Horseshoe. The vehicle crew fires its' .50 caliber machine gun at enemy defenders. Still image from USMC combat camera film

 

Camp Pendleton, Calif., 1943. A machine gunner of the 24th Marines, 4th Marine Division, fires at an aerial target during pre-deployment training. Still image from USMC Photo

 

U. S. Infantry Weapons of World War II, by Brunce Canfield
FM 23-65, M2 Heavy Barrel Machine Gun
"Machine Guns in the Solomons" Leatherneck Magazine, November 1943, by Capt Ralph Kennedy, USMCR
Organization of the Marine Infantry Regiment, 1942, 1943, 1944, 1945
D-, E-, F-, and G-series Tables of Organization, Marine division

 

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