Can you measure the barrel from the muzzle to the front of the closed bolt? Push a cleaning rod down the barrel until it hits the front of the closed bolt and measure that. A carbine has a 22 inch barrel exactly. Many cut down barrels are close to but not exactly 22 inches.

I don't have my references here to check serial number ranges for M1896 carbines but Butlers said it might not be in that correct range. Sometimes a true carbine can be a rogue one outside the known range but don't count on it. Barrels can also be changed.

The stock, though, is a M1896 carbine stock with the spring in front of the barrel band and the flared bolt handle cut out. The hand guard is nice.

So, it may be a pieced together carbine cut down from a Krag rifle.

If you are able to give us more pictures, it will answer some questions. Nice piece, regardless!