M256 (120 mm)

Description

Vehicles equipped with this weapon

• M60 AMBT
• M1A1
• M1A2 Abrams

General info

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Available ammunition

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American ammunition

Penetration statistics
Ammunition	Type ofwarhead	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

Shell details
Ammunition	Type ofwarhead	Velocity(m/s)	ProjectileMass (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°

Export ammunition

Penetration statistics
Ammunition	Type ofwarhead	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 ofwarhead	Velocity(m/s)	ProjectileMass (kg)	Fuse delay(m)	Fuse sensitivity(mm)	Explosive Mass(TNT equivalent) (g)	Ricochet
							0%	50%	100%
KE-W	APFSDS	1,585	4.00	N/A	N/A	N/A	78°	80°	81°

Comparison with analogues

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Usage in battles

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Pros and cons

Pros:

• M829, KE-W (on the M60 AMBT), and M829A1 (on the M1A2 Abrams) are amongst the most powerful shells in the game, with M829A1 having the third highest penetration after the German DM53 and the Italian CL3143.
• 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 with devastating (and often hilarious) results. A direct hit isn't needed either due to the large amount of explosive filler and wide blast radius.
• Reload is comparable to other NATO MBTs - 7.8 seconds stock and 6 seconds with an aced crew.
• Relatively wide selection of shells - 1 APFSDS shell (M829) and 1 HEAT-FS shell (M830) on the M1A1, 2 APFSDS shells (M829 and M829A1), 1 standard HEAT-FS shell (M830) and 1 HEAT-MP shell (M830A1) on the M1A2 Abrams, the M60 AMBT gets access to the powerful KE-W APFSDS shell and the M830 HEAT-FS shell.
• M830A1 is the fastest HEAT based shell in the game with a muzzle velocity of 1,400 m/s.
• Extremely high muzzle velocity on M829, KE-W, and M829A1 makes longe range sniping a satisfying experience - M829 has the highest muzzle velocity out of the 3 APFSDS shells available.
• 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.
• The reload isn't very impressive compared to contemporary tanks like the Leopard 2A5/6, the Strv 122, the Ariete and the Leclerc. The Type 90 and Challenger 2 beat it by a full second.
• M830A1 self-destructs at 4.5 kilometres - helicopters can engage the M1A2 way beyond that range.

History

In 1972, as the a 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.

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

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See also

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• reference to the article about the variant of the cannon/machine gun;
• references to approximate analogues by other nations and research trees.

External links

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)