Here is some info on the accuracy of the M1917 from long ago. Not complete but may provide some useful info:
M1917 vs 1903 Accuracy
I have often wondered how a new M1917 would stock up to a new M1903 accuracy wise. I mean service rifle to service rifle, not service vs National Match. I never owned a new M1917 (only an unserviceable one) and a couple of well used M1903 and never at the same time so could not make a comparison. I recently ran across an article in the "Dope Bag" of the AMERICAN RIFLEMAN magazine for January 1940 that provided some information. To quote from the opening paragraph:
"D.C.M Rifles. Beginning in mid summer we started getting a line on various Model-1917 rifles as sold to N.R.A members by the D.C.M office. We fired half-dozen of them at 100 yards principally with National Match 1932 and F.A. 1931 ammunition. Three of these rifles were as issued, while the others had been converted into 30-06 sporters."
What followed was a lengthy detail of the firing procedures and the results. Unfortunately, the same procedure (type of ammo, number of shots per group, etc were not uniform ) so the results are skewed. This is admittedly a very small sample so results are not truly definitive-but it's the best I could find. I shall summarize briefly, for what it's worth. I discarded the information from the sporterized rifles for I was interested in the "as issued" rifle data, and sporterized rifles offered not the kind of info I ws seeking.
The ammunition used was:
FA 1931
M1
Ball
NM 1939
RA Commercial
FA 1933 M1 Ball
Unfortunately not all groups were fired with the same ammo nor were the same number of rounds fired.
*Rifle number 1 was a Remington M1917 - as issued.
Twelve 10 shot groups with all types of ammo =3.78 inches
*Rifle number 2 was a Winchester M1917 -as issued.
Six 10 shot groups with all types of ammunition = 4.22 inches
*Rifle number 3 was aM1917 -manufacturer unidentified.
Two 10 shot groups = 4.54 inches
*Rifle number 4 was a M1903 - as issued
Fourteen 10 shot groups = 3.71 inches.
* Rifle number 5 was National Match M1903
Fourteen 10 shot groups= 4.58 inches
It should be noted that only FA 1931 and FA 1933 M1 ball was fired in this rifle. This would skew the report further since no NM ammo was used.
The best groups were fired in Rifle number 1 at 10 shots with NM1939 ammo= 2.72 inches and 10 shots of RA commercial= 2.95 inches.
Hope this helps