M256 (tank gun)

M256
Front view of a M256 gun on an American M1A2 SEP main battle tank during a gunnery exercise at Red Cloud Range, 2013.
TypeTank gun
Place of originUnited States
Germany
Service history
In service1985–present
Production history
DesignerRheinmetall
Watervliet Arsenal
ManufacturerWatervliet Arsenal
Produced1985–present
VariantsXM256, KM256, M256E1
Specifications
Mass1,175 kg (2,590 lb) (gun tube)
1,905 kg (4,200 lb) (recoiling gun mass)
Length5,593 mm (220.20 in) (overall)
Barrel length5,300 mm (208.66 in) (gun tube)

Shell120×570mm
Calibre120 mm (4.724 in)
Breechsemi-automatic vertical sliding-breechblock
Recoil304.8 mm (12.000 in)

The M256 is an American 120 mm smoothbore tank gun. It is a licensed-built German-designed Rheinmetall Rh-120 L44 gun tube and combustible cartridges with an American-designed mount, cradle and recoil mechanism. It is primarily used by the M1 Abrams main battle tank.