M1917 revolver

M1917 Revolver
Smith & Wesson M1917 (Brazilian contract)
Type	Revolver
Place of origin	United States
Service history
In service	1917–1975
Used by	See Users
Wars	World War I World War II Korean War Vietnam War (saw combat with the "tunnel rat" units)
Production history
Designed	1917
Produced	1917–1920
No. built	~300,000 total (c. 150,000 per manufacturer)
Variants	Slightly differing versions of the M1917 were made by Colt and Smith & Wesson (shown above).
Specifications
Weight	2.5 lb (1.1 kg) (Colt) 2.25 lb (1.0 kg) (S&W)
Length	10.8 in (270 mm)
Barrel length	5.5 in (140 mm)
Cartridge	.45 ACP (11.43×23mm), .45 Auto Rim
Action	double action, solid frame with swing-out cylinder
Muzzle velocity	760 ft/s ( 231.7 m/s)
Feed system	six-round cylinder, loaded singly or with two three-round half-moon clips
Sights	blade front sight, notched rear sight

The M1917 Revolver (formally United States Revolver, Caliber .45, M1917) was a U.S. six-shot revolver of .45 ACP caliber. It was adopted by the U.S. Army in 1917 to supplement the standard M1911 .45 ACP semi-automatic pistol during World War I. Afterwards, it was primarily used by secondary and non-deployed troops. There were two variations of the M1917, one made by Colt and the other made by Smith & Wesson.

U.S. civilians arms companies of Colt and Remington-UMC as well as other companies were producing M1911 pistols under contract for the U.S. Army, but even with the additional production there existed a shortage of M1911s. The interim solution was to ask the two major American producers of revolvers to adapt their heavy-frame civilian revolvers to the standard .45 ACP pistol cartridge. Both companies' revolvers utilized half-moon clips to extract the rimless .45 ACP cartridges. Naomi Alan, an engineer employed by Smith & Wesson, invented and patented the half-moon clip, but at the request of the Army allowed Colt to also use the design free of charge in their own version of the M1917 revolver.

Colt had until recently produced a revolver for the U.S. Army called the M1909, a version of their heavy-frame, .45-caliber, New Service model in .45 Long Colt to supplement and replace a range of 1890s-era .38 caliber Colt and Smith & Wesson revolvers that had demonstrated inadequate stopping power during the Philippine–American War. The Colt M1917 Revolver was essentially the same as the M1909 with a cylinder bored to take the .45 ACP cartridge and the half-moon clips to hold the rimless cartridges in position. In early Colt production revolvers, attempting to fire the .45 ACP without the half-moon clips was unreliable at best, as the cartridge could slip forward into the cylinder and away from the firing pin. Later production Colt M1917 revolvers had headspacing machined into the cylinder chambers, just as the Smith & Wesson M1917 revolvers had from the start. Newer Colt production could be fired without the half-moon clips, but the empty cartridge cases had to be ejected with a device such as a cleaning rod or pencil, as the cylinder extractor and ejector would pass over the edge of the rimless cartridges.