At one time I ran into a guy on one of these forums that was keeping a data base on the 1917 serial numbers. I don't remember which one but if I run across it I'll post it. I have a Remington 1917 with a serial number 671,250. It also has the inspection marks and ord bomb on the left rail. It's the highest one I've run across with the marks. There are a few without that are higher. A .375 sounds like a good project for it!