I guess it could also be 'gun iron'
An E. Remington & Sons broadsheet from 1854 lists "Matched barrels for double guns" -- Plain Iron $4.50 -- Stubs twist, plain $8.00 -- Stubs twist, fine $10.00 -- cast steel $8.00 -- and solid or drilled from single bar $15.00.

This may be a goat smile but the animal head stock is found on lots of Pieper guns