M1917 revolver

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 from Colt and one from S&W.

Background
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. 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 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.

Smith & Wesson M1917 revolver
The Smith & Wesson Model 1917 was essentially an adaptation of that company's Second Model .44 Hand Ejector, chambered instead for .45 ACP, employing a shortened cylinder allowing for use of half-moon clips, and a lanyard ring on the butt of the frame. Smith & Wesson had recently (c. 1915-16) produced the Hand Ejector, which uses their heavy .44 caliber frame, for the British Army in .455 Webley caliber due to shortages in British production facilities of standard-issue Webley Mk VI top-break revolvers.

The S&W M1917 is distinguishable from the Colt M1917 in that the S&W cylinder had a shoulder machined into it to permit rimless .45 ACP cartridges to headspace on the case mouth (as with automatic pistols). The S&W M1917 could thus be used without the half-moon clips, though the empty cases would have to be poked-out manually through the cylinder face, since the extractor star cannot engage the rimless cases.

While these revolvers were originally blued, S&W M1917 revolvers rebuilt during and after World War II may have been parkerized during arsenal rebuild or under a refurbish contract with S&W.

Later Use
After the First World War, M1917s became popular on the civilian and police market. Some were military surplus. Others were newly manufactured. Smith and Wesson kept their version in production, for civilian and police sales, until they replaced it with their Model 1950 Target.

Many civilian shooters disliked using half-moon clips. Loading and unloading the clips is tedious but obviates refilling the chamber with single rounds. Bent clips can cushion the firing pin strike and cause ignition problems. For these reasons, in 1920, the Peters ammunition company introduced the .45 Auto Rim. This rimmed version of the .45 ACP allowed both versions of the Model 1917 revolver to fire reliably without the clips. In the late 1950s and 1960s, the Colt and Smith & Wesson 1917 were available through mail order companies at bargain prices.

The military service of the M1917 did not end with the First World War. In 1937, Brazil ordered 25,000 Smith and Wesson M1917s for their military. Now out of service, surplus examples can be identified by the large Brazilian crest stamped on their sideplates. They are sometimes referred to as the M1937 or the Brazilian-contract M1917. The Brazilian model had an altered rear sight, and most were fitted with commercial-style checkered grips, though some utilized smooth grips left over from the United States contract.

Users

 * 🇧🇷 Brazil
 * 🇺🇸 United States: Used By U.S. Army and U.S. Marine Corps.
 * 🇵🇭 Philippines
 * South Vietnam: Used By MACV-SOG