Like as not these sporterized M1917 rifles were cut by a retailer, I can remember rifles cut in just this manner being adverted in catalogs many years ago. I think Sears Roebuck offered them at one times for around $35.


BTW
I checked Hatchers Notebook and the 1939 loading of the .30/06 would have been a 150 gr bullet at 2700 fps, they standardized the 152 gr at 2800+ in 1940.