That top thing is a barrel band with a built in sling holder. Toy or not? It doesn't look like it has been off the gun long, not enough rust and corrosion. Maybe from a reproduction muzzle loader? On second thought, maybe not a muzzle loader since the sling thing would block the ramrod. That would make it one of the 45/100 Straight wall class cartridges and a single shot if it isn't a toy. Monty