Thompson Autorifle

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Thompson Autorifle Model 1923 (top) and SMG Model 1921 Thompson 21 and Rifle.JPG
Thompson Autorifle Model 1923 (top) and SMG Model 1921

The Thompson Autorifle was a semi-automatic rifle that used a Blish Lock to delay the action of the weapon. It was chambered in .30-06, with the 1923 model in 7.62×54mmR Russian rifle rounds.

The .30-06 Springfield cartridge, 7.62×63mm in metric notation and called ".30 Gov't '06" by Winchester, was introduced to the United States Army in 1906 and later standardized; it remained in use until the early 1980s. The ".30" refers to the caliber of the bullet in inches. The "06" refers to the year the cartridge was adopted—1906. It replaced the .30-03, 6mm Lee Navy, and .30-40 Krag cartridges. The .30-06 remained the U.S. Army's primary rifle and machine gun cartridge for nearly 50 years before being replaced by the 7.62×51mm NATO and 5.56×45mm NATO, both of which remain in current U.S. and NATO service. It remains a very popular sporting round, with ammunition produced by all major manufacturers.

7.62×54mmR Russian rimmed rifle cartridge

The 7.62×54mmR is a rimmed rifle cartridge developed by the Russian Empire and introduced as a service cartridge in 1891. Originally designed for the bolt-action Mosin–Nagant rifle, it was used during the late Tsarist era and throughout the Soviet period to the present day. The cartridge remains one of the few standard-issue rimmed cartridges still in military use and has the longest service life of all military-issued cartridges in the world.


Several prototypes of the Autorifle were submitted by Auto-Ordnance to the military for the semi-automatic rifle trials, but it was not adopted. The Autorifle Model 1929, in .276 Pedersen, was tested in a competition with the rifles by J.D. Pedersen (delayed blowback) and John C. Garand (gas-operated), which culminated in the adoption of the M1 Garand.

Auto-Ordnance Company

Auto-Ordnance is a U.S. arms development firm founded by retired Colonel John T. Thompson of the U.S. Army Ordnance Department in 1916. Auto-Ordnance is best known for the Thompson submachine gun, notorious as a gangster weapon of the Roaring Twenties and famous as a military weapon of the Allied forces in World War II.

.276 Pedersen cartridge

The .276 Pedersen (7×51mm) round was an experimental 7 mm cartridge developed for the United States Army. It was used in the Pedersen rifle and early versions of what would become the M1 Garand.

John Douglas Pedersen was a prolific arms designer who worked for Remington Arms, and later for the United States Government. Famed gun designer John Moses Browning told Maj. Gen. Julian S. Hatcher of U.S. Army Ordnance that Pedersen "was the greatest gun designer in the world".

On the positive side, the Autorifle action avoided the complexity of recoil-operated and gas-operated actions. On the negative side, the Autorifle required lubricated ammunition for proper functioning and the ejection of spent cartridge casings was so violent as to be hazardous to bystanders. [1]


For reloading, the Thompson Autorifle uses an interrupted screw delayed blowback operation where the bolt has 85° angled interrupted rear locking lugs that have to overcome a rotation of 110° ( 90° to unlock before the angle blend of 70°/40° and 6°) that delays the action until the gas pressure drops to a safe level to eject. The bolt cocks the striker on opening (a la Mauser) and fires from a closed position. When firing the trigger when pulled pushes a lever connected to a sear to fire the weapon. The receiver is of a round section with the safety switch at the rear along with the rear sight. The magazine is stripper fed holding 5 rounds and lubricated by oiled pads, later prototypes used 20 round M1918 BAR magazines. [2]

Interrupted screw Mechanical device used to effect a closure using a partial rotation

An interrupted screw or interrupted thread is a mechanical device typically used in the breech of artillery guns. It is believed to have been invented in 1845. The system has also been used to close other applications, including the joint between helmet (bonnet) and breastplate (corselet) of standard diving suit helmets, and the locks of diving chambers.

BSA Autorifle

The BSA Autorifle was a British automatic rifle designed by Birmingham Small Arms Co. This rifle was manufactured by BSA under their licensing agreement with the Auto-Ordnance Corp. It was offered for British Army trials during the 1920s. [3]

The weapon was an improved derivative of the Thompson Autorifle that could be operated manually if the two curved 'shutters' around the bolt head are moved into the down position, the mechanism is disconnected and the rifle can be used as a manual loader. This facility was a requirement in self-loaders offered for British trials at this period. The weapon took part in trials during 1927 against a Colt made Thompson, an 'improved' BSA Thompson, A gas operated BSA and the Farquhar Hill. Although in 1928 reports it narrowly beat the 'improved' BSA and the Farquhar Hill in the third place, It never advanced past prototype stages as none were found acceptable and development of the BSA Autorifle waned.

BSA Guns Ltd, a licensee of protecting the patents of the Thompson Autorifle made a handful of the 1923 model Thompsons as 'heavy rifles' with folding bipods and finned barrels. Surviving examples suggest there were Rifle and Light Machine Gun variants and 6 of both types were manufactured. The first examples were made in 1924 and an 'improved' variant in 1926. The 'improved' BSA Thompson had a shorter operation with a straight pull cocking handle installed at the rear of a cocking sleeve.

The BSA Autorifle is a delayed blowback operated rifle chambered in the .303 British round and fed from a removable 10 round box magazine. Much like its predecessor, it uses a bolt with 85° angled threads delayed by a 90° twist to unlock from a bronze nut until the gas pressure drops to a safe level to eject. The bolt cocks the striker on opening (a la Mauser) and fires from a closed position. When firing the trigger when pulled pushes a lever connected to a sear to fire the weapon. The receiver is of a round section with the safety switch at the rear along with the rear sight.

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Pedersen rifle

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StG 45(M) assault rifle

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Cadet rifles are generally .22 caliber, bolt-action rifles used by military cadets and others for basic firearms and marksmanship training. They also come in semi-automatic versions. And, they are often miniature .22 caliber versions of standard issue service rifles. Older 19th century cadet rifles were simply smaller and lighter versions of standard issue service rifles designed to fire reduced power cartridges.


  1. Julian S. Hatcher, Hatcher's Notebook, MSPC 1947, pp.44-46, 155-156, 165-166.
  2. Tracie L. Hill, Thompson: The American Legend 1996 by Collector Grade Publications Inc. Cobourg, Ontario Canada, ISBN   0-88935-208-9, pp.6-14, 31-36.
  3. Rifles of the World, Page 579