M256 (120 mm)

Description

The 120 mm M256 is an American tank cannon used in its top rank vehicles. It is most famously used by the American M1 Abrams series of tanks since its installation in the M1A1 Abrams model, though it has saw usage in older American tanks like the M60 main battle tank.

It is based off the Rheinmetall L/44 cannon, though it is license-produced in America with a simplified design.

Vehicles equipped with this weapon

• M60 AMBT
• M1A1
• M1A1 HC
• M1A2 Abrams

General info

Tell us about the tactical and technical characteristics of the cannon or machine gun.

Available ammunition

American ammunition

Penetration statistics
Ammunition	Type of warhead	Penetration @ 0° Angle of Attack (mm)
		10 m	100 m	500 m	1,000 m	1,500 m	2,000 m
M830	HEATFS	480	480	480	480	480	480
M830A1	HEATFS	350	350	350	350	350	350
M829	APFSDS	491	488	481	473	464	454
M829A1	APFSDS	598	596	589	580	570	560
M829A2	APFSDS	629	627	619	610	601	590

Shell details
Ammunition	Type of warhead	Velocity (m/s)	Projectile Mass (kg)	Fuse delay (m)	Fuse sensitivity (mm)	Explosive Mass (TNT equivalent) (g)	Ricochet
							0%	50%	100%
M830	HEATFS	1,140	13.1	0.05	0.1	2,360	65°	72°	77°
M830A1	HEATFS	1,410	11.4	0.05	0.1	1,390	65°	72°	77°
M829	APFSDS	1,670	3.94	N/A	N/A	N/A	78°	80°	81°
M829A1	APFSDS	1,569	4.64	N/A	N/A	N/A	78°	80°	81°
M829A2	APFSDS	1,680	4.64	N/A	N/A	N/A	78°	80°	81°

Export ammunition

Penetration statistics
Ammunition	Type of warhead	Penetration @ 0° Angle of Attack (mm)
		10 m	100 m	500 m	1,000 m	1,500 m	2,000 m
KE-W	APFSDS	583	579	569	556	542	528

Shell details
Ammunition	Type of warhead	Velocity (m/s)	Projectile Mass (kg)	Fuse delay (m)	Fuse sensitivity (mm)	Explosive Mass (TNT equivalent) (g)	Ricochet
							0%	50%	100%
KE-W	APFSDS	1,585	4	N/A	N/A	N/A	78°	80°	81°

Comparison with analogues

• Rh120 L/44 (120 mm) - The original basis of the M256, the Rh120 L/44 matches many aspects of the American gun down to the reload rate. However, the M256 is vastly superior in APFSDS penetration performance due to the M829A1 round.
• Rh120 L/55 (120 mm) - An elongated version of the Rh120 L/44, the L/55 can exceed the M256 in APFSDS penetration and muzzle velocity values, but suffers in reload time.
• 2A46M-5 (125 mm) - This Soviet cannon is the only one in the tech tree able to come close to the M256 in APFSDS performance, but is still lacking and has a longer reload time than the M256. However, all of its chemical rounds are superior compared to the HEAT-FS the M256 can fire.
• L30A1 (120 mm) - This British cannon comes close to the M256 in terms of APFSDS penetrations alongside a slightly faster reload rate. However the only alternative chemical weapon is HESH, which means the gun must choose to focus in the armor-piercing capabilities of the APFSDS rounds or in the explosive powers of the HESH to do its damage.
• Type 90 L/44 (120 mm) - Another license-production version of the Rh120 L/44, this Japanese cannon is severely lacking compared to the M829A1 round fired by the M256. However, the gun's weapon platform in the Type 90 tanks have autoloaders to allow a way faster firing rate compared to Rh120 and M256 tanks.
• ZPT98 (125 mm) - Like the Soviet 2A46M-5, though this Chinese cannon has a much better APFSDS round available at the cost of a longer reload and no gun-launched ATGM available.
• OTO Breda 120/44 (120 mm) - This Italian tank cannon fires a fast and hard-hitting APFSDS round out of a 120 mm L/44 cannon, despite having similar handling characteristics as the M256.
• GIAT CN120-26 F1 (120 mm) - This French tank cannon has slightly lower APFSDS performance than the M829A1 round, but has a reload rate of 6 seconds between round. Otherwise, performance are quite similar in terms of HEAT-FS performance.
• Kan Strv 122 (120 mm) - See Rh120 L/44 entry due to near-identical performances.

Usage in battles

Describe the cannon/machine gun in the game - its distinctive features, tactics of usage against notable opponents. Please don't write a "guide" - do not impose a single point of view, but give the reader food for thought.

Pros and cons

Pros:

• M829, KE-W (on the M60 AMBT), M829A1 (on the M1A1 HC) and M829A2 (on the M1A2) are powerful shells,.
• The M256 on the M1A2 Abrams has access to the high velocity, proximity-fused M830A1 HEAT-MP shell, enabling the M1A2 to engage helicopters and low flying aircraft.
• Reload is comparable to other NATO MBTs - 7.8 seconds stock and 6 seconds with an aced crew.
• Relatively wide selection of shells - M829 and M830 on the M1A1, M829, M829A1, M830 and M830A1 on the M1A1 HC, M829, M829A2, M830 and M830A1 on the M1A2 Abrams. The M60 AMBT gets access to the powerful KE-W APFSDS shell (which is a tungsten based M829A1 shell, without the depleted uranium tip) and the M830 HEAT-FS shell.
• M830A1 is a fast HEATFS shell with a muzzle velocity of 1,400 m/s.
• Extremely high muzzle velocity on M829, KE-W, M829A1 and M829A2 makes longe range sniping a satisfying experience.
• Great gun handling characteristics - the gun elevates towards +20 and depresses towards -10 very quickly.
• Very effective stabiliser - does not stop working at high speeds.

Cons:

• Poor stock grind - enemy tanks are very capable of withstanding M830 HEAT-FS.
• M830A1 is not effective against enemy MBTs - it only has 350 mm of chemical-based penetration.
• The M256 on the M1A1 Abrams and M60 AMBT do not get access to the M829A1 APFSDS shell and the M830A1 HEAT-MP shell.
• M830A1 needs to travel a certain distance to arm the fuse - unable to engage helicopters at close range, except for a direct hit.
• Average reload for a NATO tank. The reload time is equal to the Leopard 2A5/6, the Strv 122's, the Ariete's, and the Leclerc's. An aced Challenger 2 and Challenger 2 (2F) can beat you by a full second, the Type 90 and Type 90 (B) (due to their autoloader) by a full 2 or 3 seconds, depending on your crewskill
• M830A1 self-destructs at 4.5 kilometres - helicopters can engage the M1A2 way beyond that range.
• M830A1 requires a direct hit for maximum effectiveness - near hits result in little to no damage to the enemy target

History

In 1972, as the replacement to the cancelled MBT-70 and XM-803 was beginning development by Chrysler and GM, a 120 mm smoothbore gun had been considered. However, the developing gun by West Germany was not expected to be produced in time to meet the scheduled production timeline, and so the 105 mm M68 was retained as the main armament for the upcoming design. In 1976, during the decision on which company will receive the contract to produce the XM-1 tank, a separate decision was made for the tank to be able to accommodate a 120 mm gun in the future, either the British 120 mm rifled gun or the German smoothbore gun. On October 28th, the XM-1 designs were modified with this new requirement. Chrysler eventually won the contract to produce the tanks, but they were armed with the 105 mm M68A1.

A diagram image of the M256 cannon.

The German Rheinmetall 120 mm was eventually chosen to become the next tank armament for US tanks. Receiving a license to produce it, the Watervliet Arsenal produced the Rheinmetall cannon as the M256. With the original Rheinmetall design considered overly complex and expensive, the M256 had been redesigned with fewer parts.

Media

Excellent additions to the article would be video guides, screenshots from the game, and photos.

See also

• Rh120 L/44 (120 mm) - The cannon the M256 was based off of.

External links

• [inetres.com] Gary's Combat Vehicle Reference Guide - M256 120mm Smoothbore Gun

References

Citations

Bibliography

• Hunnicutt, R.P. Abrams: A History of the American Main Battle Tank. Presidio Press, 1990
• Zaloga, Steven. M1 Abrams Main Battle Tank 1982-1992. Osprey Publishing Ltd., 1993

USA tank cannons
20 mm	M139
25 mm	LW25 · M242
37 mm	M3 · M5 · M6
57 mm	M1
75 mm	M2 · M2 Howitzer · M3 · M6 · M1897A4 · XM274
76 mm	M1 · M7 · M32 · T185E1
90 mm	M3 · M3A1 · M36 · M41 · M54 · T15E1 · T15E2 · T54 · T208E9
105 mm	M4 · M68 · M68A1 · M68A1E8 · T5E1 · T5E2 · T140E2 · T140E3 · XM35
106 mm	M40A1C
120 mm	M58 · M256 · T53
152 mm	M81 · M162 · XM150E5
155 mm	M185 · T7
165 mm	M135
	Foreign:
20 mm	Rh202 (Germany)
57 mm	6pdr OQF Mk.III (Britain) · ZIS-2 (USSR)
105 mm	Sharir (Israel)
120 mm	IMI MG251 (Israel)