Galloper /(?)/

Gal·lop·er

Galloper

n.
  1. One who, or that which, gallops.
  2. A carriage on which very small guns were formerly mounted, the gun resting on the shafts, without a limber. (Mil.)

Phrases & Compounds
Galloper gun
a light gun, supported on a galloper, -- formerly attached to British infantry regiments.