In spite of the M1903 Springfield having been the standard US Army rifle since 1903 the need to outfit a greatly expanded force in WW1 completely outstripped the combined capacity of Springfield Armory and Rock Island Arsenal to produce sufficient M1903s. A total of some 868,000 M1903s had been produced since 1903 and Rock Island had actually suspended production and then resumed it in 1916 when war seemed inevitable.
Fortuitously the Brit pattern 1914 contracts at Eddystone, Remington and Winchester were just winding up when the US entered the war in April 1917, so there was a warm production base available with tooling and a trained workforce which got into production of the Model 1917 adapted for the .30-06 round in short order. Model 1917 production by these 3 makers totalled some 2.5 million rifles over a period of 18 months, about 3x the US arsenal production of M1903s over the previous 14 years. As it turned out most of the US Divisions in France were equipped with the "war emergency" Model 1917s, rather than the standard M1903s.
The Model 1917 turned out to be a fine battle rifle made of strong high grade steels with an elevation adjustable aperture sight, rugged sight protection and the #### on bolt closing feature which provided a mechanical assist for primary extraction, an important advantage with a hot, dirty rifle. The M1917 was so well regarded that consideration was given to adopting it as the standard US army rifle post WW1. This didn't happen for a couple of reasons. Firstly, the target shooting element championed the more refined rear sight of the M1903 which is adjustable for both elevation and windage, and secondly, because the US Govt owned production facilities for the M1903. As much as I like the M1903 for shooting, it's sighting system is inferior to that of the Model 1917 as a fighting rifle.
The Pattern 1914 rifle, which was the progenitor of the M1917, was designed to replace the SMLE, and most would agree that it had many improved features compared to the SMLE. In the case of the Pattern 1914 the Brits were awash in SMLEs after WW1, plus they had no production facilities for this rifle, which conspired against the replacement of the SMLE by the P14. As it turned out both the very advanced P14s and Model 1917s were destined to live out their service in reserve roles.
The Danish Reserve Army was the final user of the Model 1917 rifle after WW2. These rifles were held in reserve until the late 1980s/early 1990s when they were released to the surplus market and many were imported into Canada. Some Danish hallmarks included serial numbering of bolts and stocks, the use of a roll pin type front sight on some rifles and the incorporation of a milled out notch at the rear of the receiver ring on some rifles.