The thumb lever on the right side of the piece is used to make it into a single shot rifle if the lever is down, and if the lever is up it is to open the magazine of five rounds for use.  It was an attempt by the Ordinance Board to decrease the amount of ammunition used or in their eyes, wasted in combat.  Many soldiers paid for this economy with their lives against Spanish troops armed with stripper clip Mausers which had a faster rate of fire and a more powerful round.  As for getting a taller sight, S&S Firearms sells nice repro sights and a good gunsmith, though difficult to find, can do the work of replacing the front sight.  Wayne Todd :)