You might be able to use the M1icon gauge, but you would need to interpolate where the gauge reads on the M1 and where it reads on the M1917. My guess is that if you add the distance from the M1 point to the M1917 point and subtract that distance from the reading, you should be pretty close. I am making these numbers up since I don't have a gauge but if on a pristine M1 barrel you have a "0" and your reading in the M1917 is a "5" measure from "5" toward "0" the difference distance and now you have a closer number. The problem may be that you can't see the numbers on the M1917. No problem, mark the gauge where you can see it with a sharpie and again use the difference.

Dave