If you watch newsreel footage of World War II American infantry troops in combat, you’ll no doubt see many non-commissioned officers (NCOs) carrying the Thompson submachine gun. Popularly known as the tommy gun it became a favored weapon of troops in close contact with the enemy. 

Well-made and packing a powerful punch with the .45 ACP cartridge, the Thompson had a lot more firepower than any of the other submachine guns of its era that fired the 9mm cartridge. It was used from the 1920s by both law enforcement and American gangsters. In saw use all the way up to 1989’s Operation Just Cause invasion of Panama, when some troops from the 7th Special Forces Group carried the iconic weapon into combat in the invasion of Panama.

We Need a Trench Broom

The Thompson submachine gun was first designed by John Thompson in 1918. He was looking for a “one-man, hand-held machine gun” in .45 ACP as a “trench broom” for use in the bloody trench warfare of World War I. 

“Our boys in the infantry, now in the trenches, need a small machine gun, a gun that will fire 50 to 100 rounds, so light that he can drag it with him as he crawls on his belly from trench to trench, and wipe out a whole company single-handed,” Thompson wrote during the war. “I want a little machine gun you can hold in your hands, fire from the hip, and reload in the dark. You must use ammunition now available and I want it right away.”

Thompson set up Auto-Ordnance Corporation to start manufacturing the gun. Among his hires were Theodore Eickhoff and Oscar Payne who were instrumental in designing the gun. Payne designed the weapon to be able to utilize both box and drum magazines. The prototype weapon was named the “Annihilator I.” However, the war ended before the weapons could find their way into the hands of the American troops in France.

Thompson then set out to market the tommy gun to civilian law enforcement agencies, which bought it in respectable quantities. The American underworld also became enamored with the Thompson, as civilians could purchase one for the sum of $200 (about $3,000 in today’s value.) 

Perhaps the most infamous use of the weapon was during the St. Valentine’s Day Massacre in Chicago. It was during this time that the tommy gun acquired a slew of other nicknames among them, “Chicago Typewriter,” “Chicago Submachine,” “Chicago Piano,” “Chicago Style,” “Chicago Organ Grinder,” “Drum Gun,” or “the Chopper.”

A small amount of the weapons were sold to the U.S. Postal Service and U.S. Marine Corps which favored the weapon in the Banana Wars in Central America and China. 

The Thompson Submachine Gun in World War II

In 1938, with World War II fast approaching, the Thompson SMG was adopted by the U.S. military.

It came in three variants, the M1, M1A1, and M1928A1.

The main difference between the M1 and M1A1 was the bolt. M1’s bolt had a hammer and floating pin. On the other hand, in an effort to eliminate unnecessary parts the M1A1 had its firing pin machine to the bolt’s face. Both versions had the reinforced stock and protective sight wings as standard. Neither the M1 nor M1A1 accepted drum magazines.

The M1 was first produced by Savage Arms and Auto-Ordnance which simplified the weapon and cut the cost dramatically to just $44 per weapon. The M1A1 had a barrel without cooling fins, a simplified rear sight, could use only the 20- and 30-round box magazines, employed a straight blowback action and the charging handle was on the side of the receiver.

The M1928A1 had provisions for box and drum magazines. It had a Cutts compensator, cooling fins on the barrel, employed a delayed blowback action, and its charging handle was on the top of the receiver.

Eventually, the drum magazines were discontinued by the military as they were expensive and the rounds rattled around inside the drum when the soldier carrying the weapon moved. This was something that didn’t happen with the 20 and 30-round box magazines. 

Many of the weapons were sold to the British. The gun became a favorite among the Royal Marine Commandos because of its firepower. In the U.S. military, the Thompsons’ were issued to scouts, tank crewmen, and NCOs in infantry units. Airborne and Ranger battalions were issued the Thompson submachine guns more frequently due to its firepower and effectiveness in close-quarters combat that those units would often find themselves involved in.

Marine NCOs were also issued Thompson SMGs. The weapons were at first prized for the close-in firepower, especially during Japanese banzai attacks. But in thick jungle environments, the .45 ACP cartridge was unable to penetrate some of the thick foliage and trees that the Marines found themselves in. However, many Marines would still use Thompsons to great effect during the Iwo Jima and Okinawa campaigns. 

Over 1.5 million military Thompson submachine guns were produced during World War II. Eventually, the military found a replacement for the Thompson with the M3 and M3A1 “Grease gun.” While cheaper, the Grease gun was much less accurate and had a much slower rate of fire (450 rounds per minute). Grease guns, also known as “the Greaser” would still be issued to some tank crews up to the first Gulf War.

Thompson Submachine Gun Specifications and Operation 

Weight –

10.8 lb (4.9 kg) empty (Thompson M1928A1)

10 lb (4.5 kg) empty (Thompson M1A1)

Length –

33.7 in (860 mm) (M1928A1 with compensator)

31.9 in (810 mm) (M1/M1A1)

Barrel length –

10.52 in (267 mm)

12 in (300 mm) (with Cutts compensator)

Cartridge –

.45 ACP (11.43×23mm)

10mm Auto (Limited quantity of FBI conversions)

Action Blowback, Blish Lock

Rate of fire –

approx. 700-800rpm (M1928)

approx. 600-700rpm (M1A1)

approx. 900 rpm (M1921)

approx. 1,500 rpm (Annihilator)

Muzzle velocity – 935 ft/s (285 m/s)

Effective firing range – 164 yds (150 m)

Feed system –

20-round box magazine 0.4 lb (0.2 kg) unloaded

30-round box magazine 0.5 lb (0.2 kg) unloaded

50-round drum magazine 2.6 lb (1.2 kg) unloaded

100-round drum magazine

Owing An Auto-Ordnance Replica Tommy Gun

Original Thompsons are quite expensive, rare, and hard to come by because of FFL regulations. However, Auto-Ordnance produces a semi-automatic version with a longer 16.5-inch as well as a 10.5-inch barrel for sale. But those aren’t cheap and will cost between $1,900 and $4,465 per weapon. You can buy them here.