The hammer spur on this gun is finely checkered - in my opinion, too finely for practicality. A slick (sweaty/oily/greasy/muddy) thumb could easily slip off it while cocking the gun for single action firing. Of course, in military combat use a handgun is usually a last resort (or close to it), in which case it would likely be fired double-action, and nobody cares how slick the hammer spur might be when you're not pulling it back to cock the gun.
A civilian version of this gun was marketed to the general public, and a civilian "piece parts model" was also produced, apparently built of parts left over after the military contract(s) ran dry. Grips on civilian/commercial models are said to be checkered walnut or hard rubber. Wood grips on these may or may not feature a Colt medallion. Markings on commercial models differ from those on military-contract M1917s, and they may or may not feature a lanyard loop.
All M1917 revolvers were chambered for the 45 ACP cartridge (45 Auto Rim also works).
