If it's RCAF marked on the receiver and has a "C" broad arrow on the stock, it is very likely an Winchester M1917 in 30-06. A sure way to check, is to look at the top of the barrell behind the front sight base. If there is the letter "W", "R", or "E" above a flaming bomb insignia with a month and year date below it, then it is an M1917.