90 mm gun M1/M2/M3

90 mm M1
A 90 mm M1 at CFB Borden
Type	Anti-aircraft gun, anti-tank gun (M1, M2) Tank gun (M3)
Place of origin	United States
Service history
In service	1938–1960[1]
Used by	United States United States Army Canada France[2] Japan Japan Ground Self Defence Force[3]
Wars	World War II Korean War
Production history
Produced	1940 -
No. built	133,833 (M1,M2) (1940–1945) 6,648 (M1A1)
Variants	T2 M1 M1A1 M2 T7 M3 M3A1 T8 T15 later redesignated T54 T18–T21
Specifications
Mass	M1A1: 19,000 lb (8,600 kg) M2: 32,300 lb (14,700 kg) M3: 2,260 lb (1,030 kg) (gun only)
Length	M1A1: 29.6 ft (9.0 m)
Barrel length	M1: 200 in (5,100 mm) L/55 (55 caliber) M3: 186 in (4,700 mm) L/53 (53 caliber)
Width	M1A1: 13.6 ft (4.1 m)
Height	M1A1: 10.1 ft (3.1 m)
Crew	M1: 8 (1× gunner 7× loader) M2: 8 (1× gunner 7× loader)
Shell	90 x 600-615mmR M3 HE: 3.5 in × 37.44 in (90 mm × 950 mm) (M71 complete round) M3 APC: 3.5 in × 38.24 in (90 mm × 970 mm) (M82 complete round) M3 AP: 3.5 in × 32.75 in (90 mm × 830 mm) (M77 complete round)
Shell weight	M71 HE: 23.29 lb (10.56 kg) projectile, 41.93 lb (19.02 kg) complete M82 APC: 24.11 lb (10.94 kg) projectile, 42.75 lb (19.39 kg) complete M77 AP: 23.40 lb (10.61 kg) projectile, 42.04 lb (19.07 kg) complete
Caliber	90 mm (3.5 in)
Elevation	M1: -10° to +90° M2: -10° to +90° M3: -10° to +23°
Traverse	360°
Rate of fire	6 rpm in the anti-tank variant 10 rpm in the anti-aircraft variant
Muzzle velocity	M3 HE and AP: 2,700 ft/s M3 APC: 2,670 ft/s (810 m/s)
Maximum firing range	Maximum horizontal: M1A1: 62,474 ft (19,042 m) Maximum ceiling: M1A1: 43,500 ft (13,300 m)

The 90 mm gun M1/M2/M3 was an American heavy anti-aircraft and anti-tank gun, playing a role similar to the German 8.8cm Flak 18. It had a 3.5 in (90 mm) diameter bore, and a 50 caliber barrel, giving it a length of 15 ft (4.6 m). It was capable of firing a 3.5 in × 23.6 in (90 mm × 600 mm) shell 62,474 ft (19,042 m) horizontally, or a maximum altitude of 43,500 ft (13,300 m).

The 90 mm gun was the US Army's primary heavy anti-aircraft gun from just prior to the opening of World War II into 1946, complemented by small numbers of the much larger 120 mm M1 gun. Both were widely deployed in the United States postwar as the Cold War presented a perceived threat from Soviet bombers. The anti-aircraft guns were phased out in the middle 1950s as their role was taken over by surface-to-air missiles such as the MIM-3 Nike Ajax.^[4]

As a tank gun it was the main weapon of the M36 tank destroyer and M26 Pershing tank, as well as a number of post-war tanks like the M56 Scorpion. It was also briefly deployed from 1943–1946 as a coast defense weapon with the United States Army Coast Artillery Corps. Each gun cost roughly $50,000 to make in 1940 and utilized up to 30 separate contractors to manufacture.^[5]