Rambling thoughts on the United States Revolver, Caliber .45, M1917
by Greg Ritchie

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[United States Revolver, Caliber .45, M1917 *]

In 1917, when America went to war, there were not enough of the new 1911's. The government asked Colt and S&W to modify the revolvers for the .45ACP pistol round.

Colt took their New Service revolver, one that had formerly been in service with the United States as the M1909 chambered in 45 Colt, and modified the cylinder to accept half moon clips and the .45ACP round. The early Colt's had cylinders that were bored straight through and would not function reliably without the half moon clips. Later versions were chambered to head space off the case mouth and would function without the moon clips, although the cases had to be plucked individually from the chambers.

Smith and Wesson chose their Model 44 Hand Ejector 2nd Model. The cylinder was shortened and chambered for the .45ACP round with moon clips. Smith & Wesson chambered their model to head space off the case mouth from the beginning, so unlike the Colt, it would always function with individual .45ACP rounds, but like the Colt, the empties still had to be plucked individually from the chambers.

A few of side notes:

1) Both Colt and Smith & Wesson supplied versions of these revolvers to Britain in 1915. They were chambered in 455 Webley.

2) The half moon clips were patented by a Smith & Wesson employee, but at the request of the US Government, Colt was allowed to use them without paying royalties.

3) This is the only time to my knowledge that the same nomenclature was used by the US Military to describe two different pieces of equipment.

In 1937, the Brazilian government ordered M1917's from Smith and Wesson for their military. These are known as the M1937, or Brazilian Contract M1917's. They differed from the US 1917's by the addition of the Brazilian Crest on the right side of the frame, and by having checkered grips, although smooth grips are found on some of them.

In the 1920's Peters Ammunition Company developed the 45 Auto Rim cartridge specifically for the 1917's. As noted above, neither revolver would eject the .45ACP cartridge without using the moon clips because the extractor star had nothing to bear on. The 45 Auto Rim overcame this problem by adding a thick rim, the same thickness as the .45ACP rim plus the thickness of the clip, to the .45ACP case. This eliminated issues with the use of the moon clip. Bent clips could jam the revolver or soften the firing pin blow. Also it was difficult to remove spent cases from the clips without a special tool.

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[M1917 with moon clips **]

* Photograph - By Rama (Own work) [CeCILL (http://www.cecill.info/licences/Licence_CeCILL_V2-en.html) or CC BY-SA 2.0 fr (http://creativecommons.org/licenses/by-sa/2.0/fr/deed.en)], via Wikimedia Commons
** Photograph - By Mcumpston (talk)Mike CumpstonMcumpston at en.wikipedia [Public domain], from Wikimedia Commons