Originally Posted by DWalt

There was little time in WWI to quibble over revolver parts interchangeability. Guns were needed in a hurry, and both Colt and S&W had the capability to supply satisfactory revolvers which were already in production.

BTW, in the 1906-07 Army pistol trials, the Colt New Service and the S&W triple-lock were entered. For various reasons, the Colt revolver won out, which resulted in the later adoption of the Colt New Service revolver (as the Colt Model 1909, in .45 M1909) as a stopgap measure for use during the Philippine campaign, as the Model of 1911 autopistol had not yet been adopted. Aside from its chambering, the Colt Model 1909 and the WWI Colt Model 1917 are much the same gun.