The AN/M2 .50-caliber machine gun, while not the most recognized, played a vital role for U.S. forces in World War II.
It was utilized from December 7, 1941, to August 18, 1945, marking its presence in the final shots fired from B-32 Dominators.
The .50-cal. AN/M2 functioned on air, land, and sea, participating in every major global battle. This consistent involvement in all theaters of operations uniquely distinguishes it from other U.S. military firearms of the era.
- Came of Age in the Pacific War
- Taking the Fight to Germany
- P-51 Vs Arado Ar 234.
- .50 cal The Defensive Wall
AN/M2 .50 Cal Came of Age in the Pacific War
John M. Browning originally devised the AN/M2 .50-cal. machine gun, deriving from the 1917 Model .30-cal. machine gun.
The design, short-recoil-operated and belt-fed, proved successful even in World War I’s final weeks. Responding to General John J. Pershing’s appeal for a larger caliber, Frankford Arsenal magnified the .30-cal. cartridge, crafting the 12.7×99 mm.
Today, we know it as .50 Browning Machine Gun (BMG). Consequently, Browning enlarged the M1917’s design to accommodate the new cartridge.
Completing the design in 1918, the water-cooled Model 1921 WC entered service by 1921. In May 1923, an air-cooled variant was standardized, albeit feeding only from the left.
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Browning amended the design for either-left-or-right feeding to accommodate aircraft’s tight spaces. Thus, the Model 1923 was standardized for “Army/Navy” use, becoming the AN/M2 aircraft machine gun on October 5, 1933.
575 Rounds Per Minute
It featured a lighter bolt and a considerably lighter 36″ barrel, enabling a higher cyclic rate than the M2HB, its ground combat counterpart.
While the M2HB discharged 450 to 575 rounds per minute, the AN/M2 could achieve nearly 850. Despite its barrel lacking the M2HB’s heat-dissipating features, the AN/M2 .50-cal. was designed for high-altitude, cool-temperature, and rapid-airflow operations, minimizing overheating risks.
Moreover, it was 23 lbs. lighter than the 84-lb. M2HB. Its unique ventilated barrel jacket and muzzle booster also distinguished its appearance from the M2HB.
The AN/M2 could function on a rigid mount for offense or a hand-operated mount for defense, with firing options of mechanical trigger or electrical solenoid.
$61.4 Million Contract
In 1939, the U.S. Congress significantly boosted funding for the rapidly growing U.S. Army Air Corps, necessitating increased aircraft machine gun production.
Consequently, the Ordnance Dept. granted General Motors (GM) a $20 million educational contract to adapt and equip its factories.
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Then, GM received a $61.4 million contract in September 1940 to manufacture 71,225 machine guns, including the AN/M2, across four types.
Subsequently, GM plants, specifically Frigidaire in Dayton, Ohio, and A.C. Spark Plug in Flint, Michigan, initiated AN/M2 production.
Additionally, GM’s Brown-Lipe-Chapin Division in Syracuse, New York, produced the AN/M2 .50-cal., joining other manufacturers like High Standard, Savage Arms, Buffalo Arms, Kelsey-Hayes, and Colt.
As ominous war clouds gathered over Europe and Asia, production of the AN/M2 notably escalated.
When the Japanese navy attacked military installations on Oahu, including Pearl Harbor, Americans valiantly fought back using all available arms.
Even though M1903 rifles and M1911A1 pistols were utilized, the AN/M2 machine gun emerged as the day’s hero.
Across the island, machine guns were quickly deployed in ad-hoc positions, swiftly demonstrating their efficacy. At Hickam Army Airfield, AN/M2s, intended as B-17 defensive weapons, were strategically positioned within a bomb crater, aimed skywards.
Meanwhile, on Ford Island, sailors and Marines swiftly retrieved .30-cal. and .50-cal. AN/M2s from storage, deploying them in makeshift positions crafted from sandbags, wood, and sometimes tent canvas.
Specifically, one position on Ford Island showcased AN/M2 .50-cals., mounted using an adaptor system, equipped with a rubberized buttpad, a side pistol grip/trigger mechanism, and a tower for a telescopic sight.
Sewage Line Ditch
Fourteen miles northeast at Naval Air Station Kaneohe Bay, sailors hastily established temporary fighting positions for AN/M2s.
In a sewage line ditch, five sailors deployed a pair of AN/M2s, using framing structures as makeshift platforms and ropes to secure the guns.
On Patrol Squadron (VP) 11’s nearby parking ramp, CPO John William Finn directed sailors to set up several AN/M2s on instructional/training tripods.
As the squadron’s top aviation ordnanceman, Finn was not only knowledgeable about the guns but also had full access to them and their ammunition.
Over the next two hours, Finn personally operated an AN/M2 .50-cal., effectively targeting attacking Japanese aircraft.
Despite being in an exposed position, drawing return fire, and sustaining injuries, the 32-year-old continued to fight.
After the raid and receiving minimal medical attention, Finn oversaw the re-arming of returning aircraft. Subsequently, nine months later, Finn received the Medal of Honor for his actions on December 7, 1941.
Climbed to 8,000 Feet
U.S. Army Air Corps aviators effectively utilized the AN/M2 .50-cal on that impactful day. The 47th Pursuit Squadron, conducting remote field gunnery training, was temporarily based near Haleiwa on Oahu’s north shore.
As Wheeler Army Airfield endured bombings, several pilots from the squadron hurried 10 miles to Haleiwa, taking airward opposition against the enemy.
However, only .30-cal. ammunition was available at that location. Second Lts. George S. Welch and Kenneth M. Taylor ascended in P-40 Warhawk fighters, initially with only their wing guns loaded.
Once airborne, they climbed to 8,000 feet, navigating south to Barber’s Point, and there, spotted a dozen “Val” dive-bombers.
Despite facing daunting six-to-one odds, both pilots courageously attacked. Each successfully downed an enemy dive-bomber before rapidly depleting their ammunition.
Distinguished Service Cross
They then traveled 13 miles north, landing at Wheeler Army Airfield, where ground crewmen replenished their weaponry.
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Without refueling, and armed only with fresh ammunition, both pilots returned to the skies. Engaging in dogfights over Wahiawa, Welch ultimately downed four enemy aircraft, while Taylor secured two confirmed and two probable kills.
For their remarkable heroism, both were honored with the Distinguished Service Cross.
The United States declared war on the Empire of Japan the day following the Pearl Harbor attack. The AN/M2 .50-cal., having proven its efficacy on December 7, quickly resumed its duties above the Pacific.
Beginning in February 1942, the U.S. Navy initiated a sequence of “hit-and-run” aircraft carrier raids. These operations targeted remote island outposts within Japan’s oceanic empire, commencing with the Marshall and Gilbert islands.
The AN/M2 .50 was instrumental in every key Pacific conflict, from the Coral Sea and Midway Battles to the exhaustive six-month Guadalcanal campaign.
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Furthermore, it significantly impacted the battles for New Guinea and the Philippines.
Notably, this weapon downed Admiral Isoroku Yamamoto on April 18, 1943. Additionally, during the Great Marianas Turkey Shoot in June 1944, the AN/M2 .50 downed hundreds of Japanese aircraft.
It also participated in sinking the super battleships Musashi and Yamato. Moreover, it equipped submarines, PT boats, and B-29s, which brought strategic bombing to Japan’s home islands.
The weapon was omnipresent. Similarly, in the China-Burma-India theater, it offered critical contributions. For instance, former U.S. Navy pilot James H. Howard, while in the Flying Tigers, used the AN/M2 .50-cals in a P-40 Warhawk to down six Japanese aircraft.
The .50 Cal came of age.
AN/M2 .50 Cal Taking the Fight to The Third Reich
Advancing one and a half years, Howard had become a U.S. Army major in the European Theater of Operations (ETO). As the 356th Fighter Squadron’s commanding officer in England, he frequently flew combat missions over the Third Reich.
On January 11, 1944, during a bomber escort mission to Oschersleben, Howard single-handedly attacked 30 German fighters.
He used his P-51B Mustang and its six .50-cal. AN/M2s in its wings, lacking altitude or surprise advantages.
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Engaging in a 30-minute dogfight against opposing Luftwaffe fighters, he destroyed at least three despite being outnumbered.
Andy Rooney, a Stars and Stripes correspondent, later hailed it as “the greatest fighter pilot story of World War II.”
Howard received the Medal of Honor for his actions that day above Oschersleben with the AN/M2 .50s. Simultaneously, the 401st Bombardment Group B-17s’ gunners above him battled for their lives using the same weapon.
AN/M2 .50 Cal The Defensive Wall of USAAF Bombers
The AN/M2 .50-cal., the primary defensive arm of USAAF bombers, participated in every raid against European targets during the war.
Consequently, it furnished thousands of gunners with the essential firepower to potentially survive modern air combat. This gun’s journey in the ETO began with Eighth Air Force raids in occupied France in August 1942.
Moreover, it defended bombers during the Operation Gomorrah raids, creating firestorms in Hamburg in July 1943.
Furthermore, it played a role in the following month during the notorious Schweinfurt–Regensburg shuttle mission. Also, it was present during the “Big Week” assault against the German aircraft industry in early 1944.
Additionally, it armed the bombers and fighters that supported D-Day and the Battle of the Bulge. Not only did it destroy a fair share of railroad rolling stock in stunning strafing missions, but it also was active as the war in Europe neared its end, concluding on April 9, 1945.
P-51 Vs Arado Ar 234.
Allied aircraft had never attacked Obersalzberg near Berchtesgaden in southern Bavaria, location of Hitler’s residence, the Berghof. Now, the time had come.
Although Hitler was absent, over 350 RAF bombers, with 98 U.S. Army Eighth Air Force P-51s’ support, executed a massive raid.
One Mustang was piloted by 1st Lieutenant Hilton O. Thompson of the 434th Fighter Squadron, 479th Fighter Group. His approach to the target had been uneventful, but nearing Obersalzberg, something unusual occurred.
Thompson spotted an aircraft flying eastward, 2,000 feet directly above him, and without hesitation, signaled his wingman to follow, climbing toward the aircraft—an Arado Ar 234.
Once 800 yards from the twin-engine bomber, Thompson fired two short bursts from his six AN/M2 .50-caliber machine guns, striking the German jet’s left engine.
Subsequently, he quickly closed in from seven o’clock astern, fired several more bursts between 600 and 300 yards, inflicting fatal damage to the Arado’s left side.
At just 200 yards away, Thompson ceased firing, pulled right, and watched the damaged jet spiral down from 24,000 feet, crashing near Berchtesgaden.
In total, he fired 1,571 rounds of .50-caliber ammunition, securing his second aerial victory.
When the war in Europe concluded two weeks later, the six AN/M2 .50s in Thompson’s Mustang were historically valued for downing a German jet bomber during the raid that destroyed Hitler’s home.
AN/M2 .50 Cal Specifications
The basic Browning aircraft machine gun, cal. .50, AN-M2, operates automatically, utilizing recoil, and is belt-fed and air-cooled. A metallic link disintegrating belt is employed for all gun firing activities. The gun suits all cal. .50 aircraft machine gun installations.
By appropriately rearranging certain components, the gun can accept ammunition from either the right or left side.
The AN-M2 aircraft machine gun measures 56.25 inches in length and weighs 61.00 pounds. Its cylindrical barrel, 36.00 inches long, features a ventilated jacket to dissipate heat.
The bore, with 8 rifled grooves and a right-hand twist, completes one turn every 15.00 inches.
Modifying the basic AN-M2 gun for manual firing involves substituting with a “spade grip” back plate. Additionally, users can switch from left-hand to right-hand ammunition feed by adjusting certain internal parts.
The M2 machine gun boasts a firing rate of 750 to 850 rounds per minute, with varied ammunition types including ball, armor-piercing, and tracer, among others.
The armor-piercing cartridge, M2, achieves a muzzle velocity of 2,840 feet per second and reaches a maximum range of 7,275 yards.
Some .50-caliber rounds can reach muzzle velocities up to 3,450 feet per second, although most are between 2,730 and 2,900 fps, creating chamber pressures around 55,000 psi.
The .50 BMG cartridge, measuring 5.45 inches in length, uses a rimless, tapered bottleneck case that is 3.91 inches long and has varying diameters at the neck, shoulder, and base. Lastly, the bullet is 2.31 inches long, has a maximum diameter of 0.510 inches, and weighs 706.7 grains.