According to Springfield Research, when Krag rifles or carbines were manufactured, the barreled actions were placed in crates with protective grease on them.  The stocks and fittings were only added right before the weapon was going to be issued.  I personally have a 1896 Carbine, marked 1895, serial 28xxx, that according to Springfield Research, was issued to the 1st US Volunteer Cavalry.  It's stock date is 1898.