Thompson submachineguns, 1945 or earlier

What this entry covers

The entry reads in full "Thompson, submachineguns, including all models, prototypes, & variations actually mfd. in or before 1945."¹ It is a broad line: it names no model, maker, calibre or serial range, and its single test is the date of manufacture, which the word "actually" stresses¹. It is listed in Section IV, which ATF heads "NFA firearms classified as curios or relics" that remain subject to the National Firearms Act³.

Several Thompsons have their own Section IV lines. The page names the "Thompson, Model 1927, semiautomatic carbine, cal. .45 ACP" and the "Thompson, Model 1928, Navy, 1921 overstamp" made by Colt¹. Post-war West Hurley production appears separately, both the Model M1 "between 1985 and 1986, having S/Ns from M100A to M717A"¹ and Model 1928 guns "manufactured in the 1970s and 1980s in West Hurley, New York."² Whether a particular firearm fits this entry depends on the ATF wording above.

Identifying it

Receiver markings separate the main production groups. Colt-made guns carry "MODEL OF 1921" on the left side with Colt's name at the rear, and Auto-Ordnance's name and New York address on the right⁴. Their serial number is on the left of the receiver and on the trigger frame⁴. The Navy conversion has the "1" of 1921 overstruck with an "8" and "US NAVY" stamped above the model name⁴.

Savage-made Model 1928 guns of 1940 to 1944 have "S-" prefixed serials. Their right-side address changed from New York to Bridgeport, Connecticut, during production⁴. On the M1 and M1A1 the maker's letters, "S" for Savage or "AOC" for Auto-Ordnance in Bridgeport, are stamped under the receiver near the front grip mount, not used as a serial prefix⁵. Both makers' M1A1 receivers carry the Auto-Ordnance name and Bridgeport address on the right side⁵.

Common confusions

• Converted Colts. The Model 1927 semiautomatic carbine was made from existing guns by removing the automatic parts and re-marking the receiver⁴. It has its own line¹.
• Later-made Thompsons. Guns made after 1945 fall outside this line's date¹; the West Hurley entries describe some of them^1,2.
• M1 or M1A1. The M1A1 bolt has an integral fixed firing pin, which did away with the separate hammer and firing pin. Many Bridgeport M1A1s were upgraded M1 receivers with a hand-stamped "A1"⁵.

History

Auto-Ordnance's own history says Colt made exactly 15,000 Model of 1921 guns under a 1920 contract, delivered from March 1921 to September 1922⁶. The same company history gives 1,387,134 M1928A1, M1 and M1A1 guns made during the Second World War, a figure we have not checked against an independent source⁶. Small Arms Review dates the formal approval of the M1A1 to 29 October 1942 and the last government acceptance to 15 February 1944⁵.

Further reading

• Iannamico's Part I⁴ is a detailed guide to Colt and Savage receiver markings, inspector stamps and serial patterns.
• His Part VII⁵ covers M1A1 makers, estimated output and the differences from the M1.
• The Auto-Ordnance history⁶ gives the company's account of the 1921 Colt contract and wartime totals.