I see no caliber markings at all. There are a couple sets of numbers in different spots on the action but nothing on the barrel. I don't see anything that looks like proof marks either.
That is a Model 1895 Spanish carbine. Spain normally marked converted rifles "Cal 7.62" on the receiver ring, so this is likely original 7mm Mauser. Measuring the muzzle will easily confirm it.
This rifle has the shorter rear sight ramp graduated to 1400 meters, and the saddle ring mounted under the wrist for a cavalry carbine. It is worth at least twice as much as the average 1916 model.
The 1916 models should be called short rifles or "musketoons".
I agree that the overall rifle appears to be an 1895 Spanish carbine. That said I wonder about the action. The presence of the gas relief port and the blank receiver might indicate the action at least comes from a post-fascist victory refurb of captured Republican rifles most commonly seen in blank receiver M1916s and known as 'second type'. I don't believe any original M1895 receivers had gas relief ports.
If your rifle is 7mm mauser, and you ever get over by Cambridge City, I'll give you a couple of boxes of ammo.
It is corrosive, so you have to clean carefully after shooting. Please pm me if you would like some of this.