What Is the Rheinmetall Rh 120? The 120mm Gun That Became NATO’s Standard Tank Armament

The Rheinmetall Rh 120 is the world’s most widely fielded main battle tank gun. Its 120mm smoothbore design became the NATO standard after the United States licensed it for the M1 Abrams as the M256, and today it arms the Leopard 2, M1 Abrams, K2 Black Panther and Turkey’s Altay. The smoothbore design eliminates spin-induced energy loss, allowing high-velocity tungsten penetrators to fly faster and more stably than rifled alternatives.

System Identity

Manufacturer	Rheinmetall Waffe Munition GmbH
Calibre	120mm
Barrel Type	Smoothbore
First Service	1979 (Leopard 2A0, German Army)
Licencees	USA (M256 for Abrams), South Korea (K2), Japan (Type 10)
Platform Users	Leopard 2, M1 Abrams, K2 Black Panther, Altay, Type 10

L/44 vs L/55

Variant	Barrel Length	Platforms	Advantage
Rh 120 L/44	44 calibres (5.28 m)	Leopard 2A4, M1A1/A2, K2	Lighter, shorter, urban manoeuvre
Rh 120 L/55	55 calibres (6.60 m)	Leopard 2A6/A7, Altay	~20% higher muzzle velocity, longer effective range

Ammunition Types

DM63 APFSDS	Tungsten dart — primary armour-piercing
DM12A1 HEAT-MP	Multi-purpose HEAT — light armour + personnel
DM11	Programmable HE — 3 detonation modes
LAHAT	Laser-guided — helicopters and light armour

Next Generation: Rh 130

Rheinmetall is developing the 130mm Rh 130 for the KF51 Panther. With an L/51 barrel, it is projected to achieve approximately 30 m/s higher velocity than DM11-equivalent rounds. This transition signals the end of the Rh 120’s four-decade dominance.