The caliber is on the top of the barrel in that model; muzzle side of the wood forearm. It will probable says "Cal 7 mm" which everone assumes is 7x57 or 7 mm Mauser. It is really 7 mm spanish. Yours looks like a early Remington Model 5 1897. Fire form your brass and reload modestly and shoot away. The sholders are different on 7 mm Spanish and 7 x 57. The Spanish cartridge shoulder is longer and when you shoot the 7 x 57 in it you get case lengthing. Everyone then thinks you have excessive head space but that isn't always so. I've just gone through this excercise and am glad I have, great fun to shoot!