Sure, I know what it is
, It is an old percussion black powder pistol made in Belgium. Other than that, haven't the foggiest. There are no known records for these old guns and Belgium supplied firearms to the world. Yours was made maybe 1840's t0 1880's, yes, it does look like it has been sleeved, don't know why or by who. It may have been done to repair a very corroded barrel and may even be a modern repair. Again there is no way to tell. Civil war?, I doubt it, but who knows, they used a vast number of different firearms in the Civil War?. Is it any type of issued military firearm? No. Sorry, with out some documentation it is just a very old black powder pistol that is in very bad condition. In the condition it is in value is 50 to 75 dollars as a wall decoration.Added: Rifle, yes now that I've re looked at the fuzzy pictures it may very well be a rifle. same information applies through.