The M2 .50 Caliber Made The B-17 A Flying Fortress

The Apple+ miniseries The Masters of the Air, which debuted in January 2024, tells the story of World War II aviators who served in the U.S. Army Air Force’s 100th Bomb Group of the 8th Air Force. The follow-up to Band of Brothers and The Pacific by producers Steven Spielberg and Tom Hanks has already been noted for its gritty realism. It features the vast armadas of the Boeing B-17 Flying Fortress during its missions over occupied Europe.

Those bombers were able to strike deep into German-held territory, hitting individual factories and other precision targets. Still, they whittled away at the fighter strength of the Luftwaffe in some of the largest and bloodiest air battles in history. The B-17 flew more than 290,000 sorties in the European theater of operations and dropped in excess of half a million tons of bombs.

Daytime Attacks

While the UK’s Royal Air Force (RAF) conducted night-time bombing raids over Germany, the U.S. 8th Air Force bombed during the day, and the B-17 proved especially well-suited for the task—yet it came at a steep price. As noted in the Apple+ series, the Flying Fortress was easy to fly and absorbed a lot of returning fire. The aircraft could be shot up and remain in the sky, and its Norden bombsight gave American forces bombing accuracy unmatched by any other nation during the war.

Newspapers hype crowed that the bomber could “drop a bomb into a pickle barrel” from thousands of meters in the air. That was a bit of hyperbole, and the truth was that only one of every ten bombs landed within close range of their target. On the second bombing raid against the ball-bearing factories at Schweinfurt in October 1943, the 8th Air Force sent more than 250 B-17 bombers at the target, yet the attackers failed to destroy the factory completely.

As further depicted in The Masters of the Air, the tactics to bomb German targets around the clock were costly. Tragically, more than 47,000 U.S. 8th Air Force crewmen were killed in those daylight raids over Germany.

Truly, A Flying Fortress

Development of what was to become the B-17 began in the mid-1930s, and it first took to the skies in July 1935. While it was already a well-armed warbird for the era, Boeing soon began to plan the development of the next-generation bomber. That led to the development of the B-29, but Boeing also continued to refine and improve the B-17. The aircraft increased in size and weight while it also received increased armor, self-sealing fuel tanks, and notably greater armament.

It also earned its now infamous nickname from a supportive journalist’s report.

The often-repeated story is that after Richard Williams, a reporter from The Seattle Times, observed the Model 299 prototype on the ground, he described it as a “15-ton flying fortress” in a photo caption. Boeing quickly responded by trademarking the name, and the rest is history.

The aircraft went on to be even more heavily armed to deal with the threats from enemy fighter aircraft after it entered service.

A Lucky Thirteen

The B-17G variation that saw service in the tail end of World War II was armed like no other aircraft before it, with up to a “lucky thirteen” M2 .50 caliber (12.7 mm) machine guns placed in nine positions located throughout the airframe, each able to fire upwards of 700 rounds per minute. This aircraft variant of the famous “Ma Deuce” was dubbed the AN/M2 (officially the “Browning Machine Gun, Aircraft, Cal. .50, AN/M2”)—and it was fitted with a substantially lighter thirty-six-inch length barrel.

Ten crew members —the pilot, co-pilot, bombardier, navigator, radio operator, and five gunners—were crammed into the small cabin for six to eight hours per mission. The main cabin was barely tall enough for the crew to stand up straight, and flying at altitudes above 27,000 feet meant the aircraft got very cold, often below freezing.

Crews had to be careful when touching the guns, which could be dangerously cold until fired. When enemy fighters approached, everyone but the pilot and co-pilot was expected to operate a machine gun.

Each B-17 initially carried around 5,000 rounds of ammunition—with the tail gunners and turret gunners having around 1,000 rounds available. According to some sources, the ammunition supply was doubled by the end of the war.

The B-17G’s thirteen machine guns were positioned throughout the aircraft to allow it to take on enemy fighters from nearly any direction, while the bombers also flew in tight formations.

There were two machine guns in the main cabin operated by the waist gunner(s) to defend from side attacks. Two more machine guns were positioned in the nose for the bombardier and navigator to operate when they weren’t conducting other duties. At the same time, twin .50 caliber machine guns were also positioned in the “chin turret” to the front of the aircraft and operated remotely.

It should be noted, too, that the bombardier was located at the extreme front end, protected only by a Plexiglas window. Just behind him, the navigator sat on a mounted table with access to maps and charts to best plot the bomber’s course during each mission. However, the B-17 was most vulnerable to a head-on attack—with many bombardiers and navigators killed in the early stages of the daytime bombing missions. The added .50 caliber machine guns provided them a chance to fire back at approaching German fighters.

Directly behind the flight deck, where the pilot and co-pilot were seated, were twin .50 caliber machine guns in a top or dorsal turret. It was the turret gunner’s job to scan the horizon for any incoming enemy fighters. A radio operator, located behind the turret, also operated one machine gun that fired upwards.

The underside of the B-17 was equipped with a Sperry ball turret, a spherical space about four feet in diameter and capable of rotating 360 degrees. After takeoff, the ball turret gunner—who was typically one of the smallest crew members—would crouch into a fetal position while entering the turret to operate a pair of machine guns. It may have provided a stunning view of the ground, but the ball turret gunner was still only protected by his flak jacket and the Plexiglas.

At the extreme end of the fuselage were two more twin .50-caliber machine guns, which the tail gunner operated. His job was to protect the rear of the aircraft from attack.

Initially, the bomber crews wore only heavy flight jackets and sheepskin flight trousers, which were about protecting the wearer from the cold at extreme altitudes. However, the effects of Triple-A (anti-aircraft artillery)—also known as flak—resulted in the development of flak jackets and even specialty helmets.

Though the B-17 was not literally a fortress in the sky, it should be remembered that sometimes fortresses need some outside support. This turned out to be the case with the B-17. The huge losses seen in raids like the one over Schweinfurt convinced the Allied leadership that the B-17 could not go to war over German-held territory unescorted. In the latter stages of the war, the P-51 Mustang fighter plane proved to be the bomber’s little friend all the way to Berlin and back.

The B-17 Flying Fortress went on to make its mark on history and became among the most famous aircraft of the Second World War. Yet, it wasn’t actually the bomber that was produced in the largest number. A total of 12,731 B-17s were produced, while 18,482 Consolidated B-24 Liberator bombers were also built by the end of World War II. However, both heavy bombers had a well-earned reputation for being the workhorses of the USAAF.

Today, there are reported to be only forty-five surviving B-17s, of which thirty-eight are in the United States. Just ten are airworthy. Among the most famous of the surviving aircraft is the “Memphis Belle,” which is currently on display at the National Museum of the United States Air Force.

Author Experience and Expertise: Peter Suciu

Peter Suciu is a Michigan-based writer. He has contributed to more than four dozen magazines, newspapers, and websites, with over 3,200 published pieces and over a twenty-year career in journalism. He regularly writes about military hardware, firearms history, cybersecurity, politics, and international affairs. Peter is also a Contributing Writer for Forbes and Clearance Jobs. You can follow him on Twitter: @PeterSuciu. You can email the author: Editor@nationalinterest.org.

Image: VanderWolf Images / Shutterstock.com.