To serve as a fill-in until a new pistol could be developed, the military turned to Colt and simply bought the Colt New Service revolver in .45 Colt.  This was a well-proven pistol and cartridge, and it was a double action.  It was decided that the New Service would be adopted to replace the failed New Army & Navy guns until a new pistol was ready.  Since the New Service was already in mass production, the military simply ordered guns with US military stamps and serial numbers on the butt.
This was the US Model 1909 revolver.
It was a standard type New Service with a 5 1/2" barrel and a bright blue commercial quality finish.
The butt was fitted with a lanyard loop and was stamped with US stamps and serial numbers.
It was marked with US Army, US Navy, and US Marine stamps.
The New Service US Army Model 1917.
When the US entered World War One, General Pershing wanted to have every US combat soldier armed with a pistol.  However, there weren’t enough Model 1911 pistols to go around, and not enough could be made fast enough.
To increase the number of pistols for use, the government contracted with Colt and S&W to produce large frame double action revolvers chambered for the standard issue .45 Automatic cartridge.  Both of these were designated Model 1917 Revolvers.
Since the .45ACP was a rimless cartridge, a revolver was unable to eject fired cases.  To allow the use of the .45ACP, stamped steel "half moon" clip devices were developed.  Each of these flat clips would hold three rounds and allow the double action revolver ejector to eject the fired cases.
To load the revolver two of the clips, each holding three rounds were dropped into the cylinder.  Once fired, the cylinder was opened and the ejector rod pushed, ejecting all six cases and the clips.
Colt built their Model 1917 on the large New Service frame.
It was a standard New Service with a 5 1/2" barrel and a dull brushed blue finish.  The early version had chambers that were bored straight through and these couldn't be fired without the flat clips since the cartridge case would fall into the chamber too far.  Later production guns had chambers cut to allow the cartridges to head space in the chamber and these could be fired by loading individual cartridges without the clips, but the gun couldn't eject them.  To eject a stick or rod was needed to push each case out.
The Model 1917 had two serial numbers.  The official US Military serial number was stamped on the butt, but Colt also stamped a Colt factory serial number on the frame below the barrel where the cylinder crane seats, on the cylinder crane, and inside the side plate.
This causes some argument among collectors about which number is the "Real" number.
The government used the butt number as the serial number and when the Model 1917 was sold as surplus in the 1960's, the butt serial number was on the government paper work.
The Model 1917 was made from 1917 into 1919.
When the War ended the Model 1917 was put into storage for possible future use.
In the 1930's there was a rash of robberies of US Post Offices, so the government took quantities of Model 1917 revolvers out of storage and gave them to the Post Office.  Most of these guns sat in Post Master safes until they were sold as surplus in the 1960's.
During World War Two, there was again a shortage of pistols, so Model 1917 revolvers were taken out of storage and refurbished and rebuilt where needed.  These were usually given a parkerized finish.
These 1917 revolvers were issued to anyone needing a pistol, including some combat troops, MP's, and others.
After the war they were again stored away until they were declared surplus in the 1960's and sold, often to National Rifle Association members through the Director of Civilian Marksmanship Program.