Tmitch - I am confused as .30 U.S. does refer to .30/40 Krag. You did have it right?
Every time I think I know something about Winchesters, there's a rifle that proves me wrong! I replied earlier to Clarkm that .30 U.S. is the .30-40 and .30 Gov't is the .30-03/06. Then you post your .30 U.S. Mod 1903 and I'm off base, again! I guess you can't count on anything being standard with old Winchesters.
That's a beautiful carbine you have there! I notice the two dots on the elevation scale of the Lyman. I read somewhere that's an indication of it being a factory installed option. Did you letter it?