Webster's 1828 Dictionary
GALLOPER
n.A horse that gallops; also, a man that gallops or makes haste. 1. In artillery, a carriage which bears a gun of a pound and a half ball. It has shafts so as to be drawn without a limbon, and it may serve for light three and six pounders.
Webster's 1913 Dictionary
GALLOPER
GALLOPER Gal "lop *er, n.
1. One who, or that which, gallops.
2.
(Mil. )
Defn: A carriage on which very small guns were formerly mounted, the gun resting on the shafts, without a limber. Farrow. Galloper gun, a light gun, supported on a galloper, -- formerly attached to British infantry regiments.
The Wordsmith Dictionary