any help appreciated..percussion gun in which hammer strikes a long rod that runs up the right side of forepiece (about 20" long rod)and has cup on end which strikes the perc cap on nipple. Barrel itself is only 14" long, rifled, looks like .45; single screw to remove barrel from steel fitting on nose of gun. Serial #625 all over parts, including screws. What is left of a faint cartouche on barrel looks like "MINIE Bte" plus unreadable date. Top of barrel is stamped "C.C". Local gunsmith thinks maybe belgian or french, 1860s or 1870s.PLEASE HELP.Pass this on to anyone you think might know what it is. THANKS!!