I'm trying to help a friend identify a rifle he inherited. It is a Remington (marked "E. Remington & Sons, Illion, N.Y." on the barrel). I believe it is a falling block type (lever on right side, when pushed down, lowers block straight down so cartridge can be inserted) and has a "Pat. Oct. 7, 1879 marked on the receiver and has a 4-digit serial number on the tang (?). It has a heavy octagonal barrel. Condition is, I would guess, NRA "Fair". Thank you for any help you can give us.