[MontanaMac]

I think that you are on the right path. How about this air gun

The Pope Brothers Rifle Air Pistol, called a rifle because of its long barrel and detachable wire shoulder stock, was manufactured in the USA circa 1874 to 1878 by the Pope brothers (Albert and his younger brother, Arthur) at the Pope Manufacturing Company, 45 High Street, Boston, Massachusetts, USA.

The handgrip is made of metal.

 

[MontanaMac]

Another image of the Pope Brothers Rifle Air Pistol

The pistol is cocked by pulling the barrel forwards. The pull rod clamp is fixed to the barrel such that pull the barrel also pulls the cocking rod forwards until the piston engages onto the trigger sear. At the same time, the barrel is held in this position by a thin section of sprung metal. Thus acting as a crude safety mechanism to save the shooters’ finger should they inadvertently pull the trigger whilst loading a slug or dart into the barrel.