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.
Type	Tank gun
Place of origin	United States Germany
Service history
In service	1985–present
Production history
Designer	Rheinmetall Watervliet Arsenal
Manufacturer	Watervliet Arsenal
Produced	1985–present
Variants	XM256, KM256, M256E1
Specifications
Mass	1,175 kg (2,590 lb) (gun tube) 1,905 kg (4,200 lb) (recoiling gun mass)
Length	5,593 mm (220.20 in) (overall)
Barrel length	5,300 mm (208.66 in) (gun tube)
Shell	120×570mm
Calibre	120 mm (4.724 in)
Breech	semi-automatic vertical sliding-breechblock
Recoil	304.8 mm (12.000 in)

The M256 is an American 120 mm smoothbore tank gun. It is a licensed-built German-designed 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.