*galloper*

n. 1. One who, or that which, gallops. [ 1913 Webster ]

2. (Mil.) A carriage on which very small guns were formerly mounted, the gun resting on the shafts, without a limber. Farrow. [ 1913 Webster ]

Galloper gun, a light gun, supported on a galloper, -- formerly attached to British infantry regiments. [ 1913 Webster ]