The U.S. .45 SMG in WWII

By the outbreak of World War II in 1939, the concept of military submachine guns was well established in Europe if not so much in America. The primary one available for the United States at the time was the Thompson .45 Auto SMG. During the interwar years the U.S. Navy had purchased about 500 of the Model 1921 and M-1928, with the U.S. Marines using them well in the several “Banana Wars” of Central America.

You’re In The Army Now

In 1939 the U.S. Army started purchasing “Tommy Guns” just as the Model 1928 evolved into Model 1928A1. These versions could have vertical or horizontal fore grips. Their barrels had muzzle brakes and adjustable rear peep sights and could accept either stick magazines or drums of 50- or 100-round capacities.

Those early military Thompsons cost the U.S. Government over $200 each — around $4,000 in today’s dollars! They were also time-consuming to manufacture. Savage, the sole maker in 1942, redesigned them. Drum magazines could no longer be used, fore grips were horizontal only, there was no muzzle brake and the rear peep sight became a mere bent piece of steel with a hole drilled into it. This new version was named M1. By 1943 with a few more changes they became the M1A1. The government’s price was reduced to about $44 each. All the Thompson M1 and M1A1 guns had 10.5″ barrels, wood buttstock and fore grips, and weighed about 10 to 11 lbs. unloaded depending on exact type. Their stick magazines came in 20- or 30-round types. The Model 1921 Tommy Guns had a 900 round-per-minute (RPM) cyclic rate but by the time of M1/M1A1, it was reduced to 700/750 RPMs.

Here is a tidbit I found intensely interesting in the book Retributions by British historian Max Hastings. For the September, 1944 U.S. assault on the island of Pelelieu he had official figures for the number of certain types of U.S. military ammunition consumed in the battle. For .45 Auto it was 1.52 million! I would suppose most of it was fired from Thompson SMGs.

The Grease Gun Arrives

By 1943 the government wanted even cheaper, easier-to-manufacture and lighter SMGs. Therefore their designers borrowed on the German and British concept of all-metal manufacture and incorporated a wire butt stock. The end result looked amazingly like a mechanic’s grease gun. Officially they were termed M3 but for 75 years mostly they have been called “grease guns.” Barrel length was 8″ and like the later Tommy Guns, their rear sights were merely perforated bent pieces of steel. Weight was about 8 lbs.

Magazines for them were stick-type holding 30 rounds. Whereas Tommy Guns were select fire, “grease guns” were full auto only.

Not long after entering combat with American forces in June 1944, it was determined the M3 charging handle was fragile. It was a crank on the receiver’s left side and was replaced with a simple hole in the bolt for the user’s finger to retract it. This change became M3A1. Either M3 or M3A1, their cyclic rate of fire was only about 400/450 RPM.

Rising Reising

Worthy of mention in the realm of .45 Auto SMGs were the M50/M55 Reising Guns used by the Marines in early World War II. The M50 had wooden stocks while the M55 had a combination wood/folding wire butt stock because they were intended for ParaMarines. Their magazines were of 12- or 20-round capacity. Interestingly, where America’s other SMGs fired from open bolts, Reising Guns fired from a closed bolt, which increased probability of hitting with first shots. Combat Marines did not care for Reising Guns due to their unreliability, perhaps mostly caused by magazines.

Goin’ Shopping

In my quest to learn about the shooting aspects of World War II firearms, with one exception I have purchased representative samples of each basic type mentioned above. My Tommy Gun is the M1 version and my “grease gun” is the M3. The exception is Reising Gun but I have fired many rounds through a friend’s Model 50. It only functioned well with one of the several magazines he had for it.

Conversely, my M1 Thompson has never had a failure to function with any ammo but the M3 has failed to work well with some cast bullet handloads. I’ve found both SMGs easy to hit targets with out to 50 yards as long as bursts are kept short.

Twice as many 9mm rounds can be carried for the same weight of .45 Autos. Therefore, 9mm SMGs eventually ruled in military forces. Conversion kits were even made so “grease guns” could fire 9mm. But, even with only limited use, .45 Auto SMGs have their place in American military history.

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