Um chopped rifles are 30".  If yours is with the original handguard it's worth some cash.  Probably 700-1600 depending on condition.   The "real" carbines are valuable as well. 

Question.  Is an 1899 serial number with a 1901 sight considered "not original" as it was probably switched out in the first couple yeArs or maybe even before it left the arsenal?  What's the deal on this.