Thompson Model 1921

firing pin cut, barrel drilled

The Thompson submachine-gun was developed as a result of efforts by a retired US General, John T Thompson, to produce a lightweight automatic rifle. Thompson wished to exploit a locking mechanism for firearms patented by John B Blish. This invention employed a sliding wedge in the bolt of the weapon to exploit the "metallic adhesion" of certain metals under high pressure, retarding the rearward motion of the bolt until pressure in the barrel had dropped to a safe level. Thompson's plans to build rifles never came to fruition, but an adaptation of the system to produce a "Submachine Gun" (the name was apparently coined by Thompson himself) which fired .45 inch pistol cartridges was more successful. The early production and marketing of the Thompson met with many difficulties. One of the first significant sales, in 1921, was to an intermediary for a group intending to illicitly export to the Thompsons to the Irish Republican Army - then fighting a guerilla war against British Forces. This weapon is one of those guns, seized many years later by security forces in Northern Ireland. The serial number on the side of the weapon has been struck-out to obfuscate the circumstances of its purchase.

Part of the IRA's 1921 purchase of 495 Thompsons, which was the Auto-Ordnance Corporation's first major sale. Inferred from the serial number

1) AUTO-ORDNANCE CORPORATION NEW YORK, U.S.A. PATENTED MARCH 9, 1915 JULY 27 1920 MAY 4, 1920 AUGUST 10, 1920 MAY 25, 1920 SEPTEMBER 7, 1920 MAY 25, 1920 OCTOBER 26, 1920 DECEMBER 28, 1920 JHB 2) MODEL OF 1921 936 [scratched out] THOMPSON SUBMACHINE GUN, CALIBRE 45 AUTOMATIC COLT CARTRIDGE MANUFACTURED BY COLT'S PATENT FIRE ARMS MFG. CO HARTFORD, CONN, U.S.A. 3) FIRE SAFE AUTOMATIC SEMI AUTOMATIC 4) TRADEMARK AUT-ORD-CO REG.U.S.PAT.OFF