Yes, the US military had two .45acp handguns.. the 1911 and the lesser known M1917. I found both of these old girls in a little tiny local auction. These were more to supplement the 1911, and supply rear line, non deployed, or secondary troops with sidearms. However, they do have a service history that stretches from WWI to Vietnam, tunnel rats in Vietnam were known to use them. Contracted by two makers, Smith & Wesson and Colt, both are very well known and popular revolver makers. The total production was around a 150,000 revolvers per maker. Quite a few of these ended up rechambered in .455 Webley or were sold off to Brazil, others have been tinkered with when sold off to the public. So to find a low production US military firearm, thats still original and in undicked shape is kind of rare. The serials on both show a 1918 build date, so if thats accurate, next year they will be a 100yrs old.
They show some use, but lock up and timing seem pretty good. I have seen newer production revolvers looser than either of these.
First up..the Colt
Their pretty close in looks and both are a double action design, are .45acp and share the name, United States Revolver, Caliber .45, M1917, but thats all they share, unlike the millions of 1911s, Garands, M1 Carbines, the M1917 Enfields, M1903s that were made, there is hardly an interchangable part between these two. True to each others design, that still shows today, there are major differences that set each apart.
Like a simple cylinder release.. on the S&W(left) you use your thumb to push forward, the Colt(right), you use your thumb to pull it back
Cylinder design and even the cylinder rotation when you squeeze a round off.
The Colt(top) cylinder rotates clockwise, the S&W(bottom) rotates counter clockwise, both from the shooters perspective.
Front sights and hammers..
Another is the barrels, the Colt has a slightly heavier barrel, but the S&W is threaded, and then pinned in place...and even the rifling twist direction between the two differ..
I'm sure by know your like GM, how do you shove an rimless ACP round in a revolver and fire it, there is no rim to catch.. If you notice the photos of the two cylinders above, there is a rim cut in each, thats where the case head spaces in the cylinder.. Colt didn't add that until around pistol serial 30k.. so.. you can use moon clips or if desperate, load rounds individually.. after firing, the rimless rounds can be a bear to remove. If the moon clip is used, the normal star extractor will pop all 6 out. Also... there is a .45 auto rim, it's a rimmed .45acp that was developed for these, no moon clip needed, and the extractor will pop them out...
A final last parting shot, the butt shot.. again.. Colt and S&W had to label it totally backwards from each other..