M6 (75 mm)

Description

The M6 is an American 75 mm tank cannon mainly used on the M24 Chaffee. It was developed from the aircraft-mounted 75 mm T13E1, which was itself a derivative of the 75 mm M3 tank gun.

Vehicles equipped with this weapon

• M24
• M24 (TL)
• ▅M24
• ␗M24
• ▄M24
• AMX-13-M24

General info

The M6 cannon was equipped with a vertically sliding semi-automatic breech block which was tapered to facilitate quick loading. The standard 75 mm calibre allowed this gun to be compatible with existing single-piece ammunition already developed for the M2, M3, and T13E1 cannons. The barrel is rifled to induce spin on fired shells which assists in accuracy. From the rear of the breech to the muzzle, the M6 is 116.38 inches long.

Due to the lightening efforts leftover from the T13E1 program, the M6 weighed a mere 410 lbs, compared to the 893 lb total weight of the 75 mm M3. One of these efforts was implementing a thinner barrel. While still retaining the accuracy and ballistic properties of the original, the barrel had a shorter service life than the M3 due to its decreased durability.

The M6 featured a T33 concentric recoil system which prevented the gun from recoiling too far, allowing it to be used in confined spaces such as the turret of the M24 Chaffee. In the M64 combination gun mount, it was paired with the 7.62 mm M1919A4 medium machine gun.

Available ammunition

M72 AP: The usual default AP shell. Decent penetration and post-penetration damage but lacks explosive filler. It is recommended to trade in for better shells once they are unlocked.

M48 HE: Useful for demolishing very lightly armoured and open-topped targets such as SPAAs and SPGs. Not recommended for use against targets with little more than very thin armour, so 2-3 shells are usually taken if needed. This shell will blow an aircraft out of the sky if it connects. Due to the mass of the explosive, it will fly slower and have a higher firing arc than AP shells.

M61 APCBC: The penultimate shell for use by the M6 cannon, it has good penetration and amazing post-penetration damage due to the high explosive mass. This shell has a reputation of destroying enemy vehicles in one shot on a decent hit. It is recommended to use this shell nearly exclusively when unlocked, for destroying enemy armoured vehicles.

T45 APCR: Useful for piercing armour that cannot be penetrated by any other armour-piercing shell. To achieve this, however, the shell trades off post-penetration damage which it limits its ability to destroy enemy vehicles quickly and effectively. Currently only available for the M6 cannon mounted on the M24 (TL).

M64 Smoke: This shell is used more defensively, fired toward enemy sniper positions to blind them or fired over or ahead of friendly forces to conceal movements. This shell is not recommended for offensive use unless in an emergency against an unarmoured target. Due to the mass of the smoke, it will fly slower and have a higher firing arc than AP shells. The smoke screen takes about 5 seconds to fully deploy and lasts around 20 seconds. Take this into consideration when using it, and try not to get caught out in the open when the smoke clears.

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
M72 shot	AP	91	88	78	67	57	49
M48 shell	HE	10	10	10	10	10	10
M61 shot	APCBC	104	101	90	78	68	59
T45 shot	APCR	139	135	121	105	91	79

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%
M72 shot	AP	619	6.3	N/A	N/A	N/A	47°	60°	65°
M48 shell	HE	463	6.3	0	0.1	666	79°	80°	81°
M61 shot	APCBC	618	6.79	1.2	14	63.7	48°	63°	71°
T45 shot	APCR	868	3.81	N/A	N/A	N/A	66°	70°	72°

Smoke shell characteristics
Ammunition	Velocity (m/s)	Projectile Mass (kg)	Screen radius (m)	Screen deploy time (s)	Screen hold time (s)	Explosive Mass (TNT equivalent) (g)
M64	381	6.9	13	5	20	50

Comparison with analogues

• 75 mm M3: The grandfather of the M6, both use the same ammunition with identical ballistic properties. The M6 has a shorter recoil length than the M3 due to its concentric recoil mechanism. The M3 is mainly mounted on the M4 Sherman family of medium tanks. The M6, mounted on the M24 Chaffee, has a slightly longer reload due to the cramped turret.

• 75 mm T13E1: The derivative father of the M6 and derived from the M3 for use as an aircraft gun, it uses the same M61 APCBC and M48 HE shells with identical ballistic properties. This gun is mainly mounted on the B-25G, B-25H, and the PBJ-1H. Compared to the M6 mounted in the M24, the T13E1 mounted in the PBJ-1H is able to reload more than twice as fast.

• 75 mm KwK40: The German 75 mm KwK 40, L/43 and L/48, cannons are mainly mounted on the long-gun members of the Pz.IV family. Both KwK 40 variants shoot the PzGr 39 shells at higher velocity than the the M6 does with its M61, so the KwK 40 will outshoot the M6 at range. The KwK40 gun will also be able to reload slightly faster than the M6.

• 76 mm F-34: The Soviet 76 mm F-34 is the standard WWII tank gun of Soviet tanks, and is mounted mainly on the T-34 medium tank family. The F-34's BR-350A/B APHEBC and BR-350SP APBC shells have a slightly higher muzzle velocity than the M61 APCBC shell, but have inferior armour penetration. T-34 mounted F-34 guns have a longer reload than M24 mounted M6 guns due to the T-34 turrets being even more cramped than the Chaffees'.

• 75 mm OQF Mk.V: The British 75 mm OQF Mk.V is virtually identical to the 75 mm M3 and the M6, being a re-bored 57 mm OQF 6-pounder, and uses the same ammunition as the American guns. The only difference is that the OQF Mk.V has a slightly lower muzzle velocity when using the M61 shell. The OQF Mk.V is mainly mounted on the Cromwell V cruiser and Churchill VII heavy tanks. Cromwell Vs armed with the OQF Mk.V can reload faster than the M24s with the M6.

• 75 mm Type 3: The Japanese 75 mm Type 3 is the Chi-Nu and Ho-Ni III's weapon of choice. It has very similar armour penetration to the M6 but keeps more power behind it at longer ranges. Type 1 APHE has a higher muzzle velocity than M61 APCBC and combined with the higher armour penetration at range means that the Type 3 will outperform the M6 at longer ranges. The Chi-Nu and Ho-Ni III are able to reload faster than the M24 Chaffee.

• Ansaldo 75 L/34: The Italian 75 mm 75 L/34 is a tank gun mounted on the P40, P40 "G.C. Leoncello", medium tanks and the 75/34 M43 tank destroyer. The Granata Preforante 75/32 APCBC shell is significantly inferior to the M61 and even the M71 shell in terms of armour penetration. The 75 L/34 is not as accurate as the M6, but is able to reload a lot faster than it.

• 75 mm SA49: The French 75 mm SA49 is carried by the AMX-13 (FL11) light tank. The AMX-13 (FL11) also gets access to the M61 APCBC shot with identical properties. The French PCOT-51P APCBC shell has a higher muzzle velocity than the M61 shot but has no explosive filler. Accuracy of the SA49 is poor at longer ranges so the M6 has a slight advantage. The AMX-13 (FL11) is able to reload slightly faster than the M24 Chafee.

• Kan m/41: The Swedish 75 mm Kan m/41 is mounted to the Ikv 72 self-propelled gun and the Ikv 73 and Strv m/42 EH medium tanks. The slpprj m/40B APBC shell is inferior compared to the M61 shot in terms of armour penetration and muzzle velocity. The M6 will be able to outperform the Kan m/41 at medium to long ranges. Vehicles armed with the Kan m/41 are able to reload faster than vehicles armed with the M6.

Usage in battles

The 75 mm M6 is an excellent anti-tank weapon at Rank II-III where it is usually utilized, and is able to still perform decently far above its tier. As with any gun, knowing your enemy's strong points and weak spots will allow you to use this gun effectively. Good muzzle velocity, armour penetration, and post-penetration damage with the M61 APCBC shell allows this gun to defeat many enemies in one shot, especially medium and light tanks. Check "Available Ammunition" for recommendations on what shells to use with this gun and how.

M24 Chaffee:

When mounted in an M24 Chaffee turret, the 75 mm M6 has access to a vertical stabilizer. This means that the M24 is able to vertically stabilize the gun for accurate firing very quickly. Depending on the circumstances, a stabilized M6 cannon can outperform on the move any other tank gun previously mentioned which does not have a stabilizer.

It not recommended to turn off the vertical stabilizer when using this vehicle.

Pros and cons

Pros:

• Compatible with an wide variety of shell options, including the excellent M61 APCBC shell
• Decent muzzle velocity
• Good accuracy
• Good penetration with AP shells
• Slightly smaller barrel and breech assembly: has a moderate to slightly low chance of taking damage if the carrier vehicle is hit
• Shorter recoiling system than the 75 mm M3
• Benefits from a vertical stabilizer (when mounted on the M24 Chaffee)

Cons:

• Slightly longer-than-average reload
• Lower accuracy and armour penetration at long ranges
• APCR is only available for the M24 (TL)
• Can struggle against vehicles with heavy or significantly angled armour
• No HEAT or APDS ammunition

History

Development of a new light tank for the US Army began in 1943 with the focus of improving the light tanks' firepower from a 37 mm to a 75 mm gun. The new light tank design, designated T24 on 29 April 1943, required a lighter-weight and shorter-recoiling 75 mm gun than that seen on the M4 Sherman's 75 mm M3.

A M24 Chaffee and its 75 mm M6 gun.

Rock Island Arsenal was tasked with the development of the new lightweight 75 mm gun. The basis of the new gun was the 75 mm T13E1, which had seen use as an aircraft mount as the 75 mm M5 on the G and H variants of the B-25 Mitchell and the PBJ-1H. The 75 mm M3 and T13E1 shared ballistic performances, but the T13E1 had thinner barrel walls which shortened barrel life and caused the gun to overheat more easily. The T13E1 utilized a T19 concentric recoil mechanism, which shortened the recoil length than the M3. These design changes allowed the T13E1 to achieve a weight of just over 400 lb, compared to the 75 mm M3's 893 lb. weight. The design was worked on with a new T33 concentric recoil mechanism in a T90 combination gun mount to fit within a light tank turret. This new gun configuration and mount was tested in Summer 1943, and proved that the gun can work inside a tank with a turret ring down to 60 inches in diameter.

When the T24 was accepted into service as the M24 Chaffee on 22 June 1944, the modified 75 mm T13E1 was standardized as the 75 mm gun M6 in a M64 combination gun mount.

An attempt was made to improve the 75 mm M6 gun in early 1945 with the 75 mm gun T21. The new gun featured a stronger breech assembly, improved firing mechanism, a fixed breech operating handle, and a hand cocking lever for the gun that was accessible to every turret crew member. The gun also featured a T13 single-baffle muzzle brake. The gun was eventually accepted as the 75 mm gun M17, but the war had ended by that point and so did the M24 production lines.

Media

Images

• 

  M24 Chaffee equipped with the 75 mm M6

See also

• T13E1 (75 mm)- Aircraft cannon the M6 was derived from
• M3 (75 mm) - Tank cannon the T13E1 was derived from

External links

Bibliography

• Hunnicutt, R.P. Stuart: A History of the American Light Tank. Presidio Press, 1992
• Zaloga, Steven. M24 Chaffee Light Tank 1943-85. Great Britain: Osprey Publishing Ltd., 2003

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)

Japan tank cannons
37 mm	Type 94 · Type 100 · Type 1
47 mm	Type 1
57 mm	Type 90 · Type 97
70 mm	Type 94
75 mm	Type 90 · Type 99 · Type 3 · Type 5 (Type I Model II · Type II Model I · Type II Model II)
90 mm	Type 61
105 mm	Type 5 (Experimental · Production) · JSW L/52
106 mm	Type 60 (B)
120 mm	Taishō Type 10 · Navy short gun · Type 90 L/44 · Type 10 L/44
150 mm	Type 38
155 mm	NSJ L/30 · JSW L/52
	Foreign:
25 mm	Oerlikon KBA B02 (Switzerland)
30 mm	Bushmaster 2 Mk.44 (USA)
35 mm	Oerlikon KDE (Switzerland)
75 mm	M6 (USA)
76 mm	M1 (USA) · M32 (USA)
88 mm	KwK36 (Germany)
90 mm	M3A1 (USA) · M36 (USA)
105 mm	L7A3 (Germany)
120 mm	Schneider-Canet 1898 (France)

China tank cannons
30 mm	ZPL02 · ZPZ02
73 mm	Type 86
76 mm	M32K1
85 mm	Type 56 · Type 63
100 mm	PTP86 · Type 59 · Type 69 · Type 69-II · ZPL04
105 mm	88B-105T · Type 83 · WMA301 · ZPL94 · ZPL98A
120 mm	122TM · PTZ89
125 mm	Type 88C · Type 99A · ZPT98
130 mm	PL59A Gai
152 mm	PL66 Gai
	Foreign:
20 mm	KwK30 (Germany)
37 mm	M6 (USA)
45 mm	20-K (USSR)
47 mm	Type 1 (Japan)
57 mm	Type 97 (Japan) · ZIS-2 (USSR)
75 mm	M2 Howitzer (USA) · M3 (USA) · M6 (USA)
76 mm	D-56T (USSR) · F-34 (USSR) · M1 (USA) · M7 (USA) · ZIS-3 (USSR)
85 mm	ZIS-S-53 (USSR)
90 mm	M3 (USA) · M41 (USA)
100 mm	D-10S (USSR)
105 mm	M68 (USA) · M68A1 (USA)
115 mm	U-5TS (USSR)
122 mm	A-19 (USSR) · D-25T (USSR)
152 mm	ML-20S (USSR)

Italy tank cannons
20 mm	Breda Mod.35 · Fucile Controcarri S Mod.39
25 mm	Oerlikon KBA B02
37 mm	Vickers-Terni 37/40 mod.18
47 mm	47/32 mod.35 · 47/32 mod.39 · 47/40 mod.38
60 mm	Cannone da 60/70 · OTO HVG
75 mm	75/18 mod.34 · 75/32 mod.37 · 75/34 mod.39 · Ansaldo 75 L/34 · OTO 75/43 mod.40
90 mm	90/53 mod.41 · Cannone da 90/50 M3A1 · Cockerill Mk.3
100 mm	Cannone da 100/17 Mod.1914
105 mm	Cannone Ansaldo da 105/25 · OTO Melara 105/52 · OTO Melara 105/55
106 mm	Cannone da 106 s.r.M40A1
120 mm	OTO Breda 120/44 · OTO Melara 120/45
	Foreign:
30 mm	Bushmaster 2 Mk.44 (USA)
37 mm	M6 (USA)
75 mm	KwK37 (Germany) · KwK40 L48 (Germany) · M3 (USA) · M6 (USA) · StuK40 L48 (Germany)
76 mm	M1 (USA) · QF 17-pounder (Britain)
90 mm	M3 (USA)
105 mm	L7A3 (Germany) · M68 (USA)
155 mm	M126 (USA)
	Hungary
20 mm	Solothurn QF.36M
40 mm	37/42M · MÁVAG 41.M 40/51
75 mm	41.M · 43.M
105 mm	MÁVAG 40/43M
	Foreign:
30 mm	2A72 (USSR) · MK 30-2/ABM (Germany)
88 mm	KwK36 (Germany)
120 mm	Rh120 L/44 (Germany) · Rh120 L/55 A1 (Germany)
122 mm	2A31 (USSR)
125 mm	2A46 (USSR)