The rifling appears to be the old style of wide lands and narrow grooves that was so popular in the 19th century. Today most every one uses equal lands and equal grooves in their barrels. Also the lock has the "Nut and Spindle" (I think they call it) arrangement securing the hammer usually only found on higher quality English firearms of that same period. Rarely found on American pieces. The architecture is perfect for a 19 century American percussion rifle. There are six gunsmiths in Sellers book with the Initials F Smith. I would vote that you have a fine original pierce from the 19th century. Now go POP A SQUIRREL!!!!!...IMHO,,,Ed