Since the rifles were cheap and the action is quite strong, the Model 1917 was gunsmithed all over the place, including by Remington, which used surplus M1917 receivers, bolts, and other parts to make its Model 30, 30S and 720 rifles.
A favorite caliber was .308 Norma Magnum, which I understand was developed specifically to allow rechambering of the Model 1917 with few or no other changes. The result is that determining the caliber of any M1917 that might have been altered is not easy.
Jim