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A Tale of Two Histories: Thompson Submachine Gun, .30-Caliber Prototype

Many inventions throughout history have seen multiple lives. A Model 1883 Gatling Gun, made in 1886, was fixed with belts and a motor in 1946 to become a test gun in what would become the Vulcan Project. A G30 semi-automatic rifle served as the basis for a prototype of the Winchester automatic rifle. Often the idea for an invention can have application in future technologies, either successful like the Gatling or unsuccessful like the G30. Regardless, their resurgence always makes a unique fusion of the past and the present. And the Cody Firearms Museum’s .30-caliber Thompson is no exception.

Yes, I typed that correctly — a Thompson submachine gun chambered in what would be designated .30 M1 caliber. But how did that happen? The story of this gun collides two World Wars and a feeble attempt at teaching an old gun new tricks.

Around 1916, General John Thompson founded Auto Ordnance in order to make a new firearm. He originally envisioned a semi-automatic firearm that would replace the bolt-action rifles that were so prevalent, but what he ultimately developed was one that has the claim of being the first commercially marketed submachine gun. The Annihilator I, as it was originally designated, was a .45 ACP automatic firearm that a person could wield on his or her own, but it was made too late for adoption in World War I. The idea though to have an automatic firearm in a pistol caliber was revolutionary and many would follow suit. After the war, the firearm was renamed the Thompson Submachine Gun and marketed commercially. The model 1921 was the first model introduced and the gun would see use for the U.S. Postal Service, Marines, and law enforcement agencies initially. But by WWII, it would be the standard issue submachine gun for the United States.

While this gun rose to popularity in the interwar period, progress on many technologies faltered. By the end of WWI, many new designs had been developed, but the drive to invent had been halted in many respects by the lack of global war. However, that didn’t stop some from trying to push innovation forward.

In March 1938, the U.S. Infantry Board had requested from the Ordnance Department a lightweight shoulder-fire rifle or carbine. However, the urgency wasn’t yet instilled in the Ordnance Department to act. Later that year, the Infantry once again raised the issue with recommendations for such a rifle. However, the Ordnance Department was of the mindset that current weaponry was sufficient, and funds weren’t available for the project. The idea continued to push forward with even the suggestion of looking into commercial designs, but it wasn’t until WWII became very real that the attitude changed to look more seriously into the project.

By June 1940, the Secretary of War, at the urging of the Infantry, gave the project the kick in the pants it needed. By then, funds had been secured and the Ordnance Department had been instructed to find a firearm with the following characteristics: 1) It had to be 5 pounds total; 2) it needed to be effective up to 300 yards; and 3) it needed to be carried by a sling or something similar. The idea was to develop a carbine that was better than a soldier’s .45-caliber Model 1911 pistol, but not as big as the infantry’s M1 Garand.

In addition to a new gun, a new cartridge was needed to be sufficient for this light rifle, bringing Winchester to the table. Winchester had decades of experience in both arms and ammunition manufacture for war and were a natural choice for developing a cartridge that would be sufficient for the new technology. Initially, Winchester recommended a .32 Winchester self-loading cartridge type. The company handmade experimental cartridges reduced down to a .30-caliber bullet. They were tested in both November and December of 1940, and examples were sent to the potential developers.


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Fast-forward to the adoption of the M1 Carbine in .30 M1 since pretty much everyone reading this knows which firearm won the race, but there were several prototypes that weren’t successful and therefore have been left on the cutting-room floor of history. One of those prototypes sits on display at the Cody Firearms Museum. This Thompson at first glance looks like a Model 1928 Thompson submachine gun. It has the machine roll mark for Auto Ordnance and most of the working parts are the same. The main differences are the barrel, bolt, receiver, and magazine.

Auto Ordnance attempted to show that what the military was looking for didn’t have to be a completely new firearm, rather a reimagining of an already in use weapon. The Thompson in the 1940s was the standard issue submachine gun and Auto Ordnance was worried that these new trials could replace their invention. It should be noted that Auto Ordnance did submit another, more viable, prototype for the trials, but the Thompson is far more interesting, as it merged two categories of firearms and failed miserably.

This Thompson, clearly marked serial No. 1, was hand-stamped and labeled .30 short rifle M1 self-loading cartridge, as the caliber designation wasn’t official yet. It was assembled around 1941, but the primary requirement wasn’t only not met, but exceeded by a factor of 2. The trials asked for a firearm to weigh no more than 5 pounds total — this prototype is about 10 to 12 pounds unloaded, and as a result, it wasn’t given much thought. But hey, it was a relatively cheap way for Auto Ordnance to try to prove a point with not much risk in the game.

And while not much more was done with this firearm, it’s on display at the Cody Firearms Museum. And at the museum, another bit of oral history gun lore emerged. According to the founding curator of the museum, when he walked Board of Trustees member William B. Ruger into the vaults, Ruger claimed he assembled that gun during his time at Auto Ordnance. Now, we wish we had more provenance to back that statement up, but if true, not only does this gun play an important role in Thompson and M1 Carbine history, but also in the history of the biggest firearms company in the U.S.


Auto Ordnance Prototype
Caliber: .30 short rifle M1 self-loading
Barrel Length: 10 inches
Overall length: 32 inches
Weight (unloaded): 10 to 12 pounds
Action: Blowback
Capacity: 20 round


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