Nope, 40mm can't be used for indirect fire. And for direct attack it severely lacks a punch to knock out fortified positions.
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Kahn, it's not funny to argue with you anymore. 94mm AA entered production in 1937 . In mid thirties no one designed heavy AT guns as they were considered unnecessary because no heavy tank existed
Hell , I dare you to prove me that 3.7-Inch QF AA was designed as a dual purpose gun and that it was designed and approved in 1928 with prooflinks. If you prove that I'll not post in this topic anymore. Until then I am assuming that you are just making "facts" from a thin air, Like Mesor with his fragmenting rounds that penetrated two inches of metal
It was also designed in 1928, and was put into production in the early 1930's.
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[During the 1920s Vickers developed the predictor, an electro-mechanical computer that took height and range data from an optical rangefinder, applied corrections for non-standard conditions and was used by its operators to visually track a target, its output predicted firing data and fuze setting via the "mag-slip" electrical induction system to dials on each gun in a battery, the gun layers moved the gun to match pointers on the dials. The 3 inch AA guns were modified accordingly.[4]
QF 3.7
In 1928 the general characteristics for a new HAA gun were agreed on; a bore of 3.7 inches (94 mm) firing 25 pounds (11 kg) shells with a ceiling of 28,000 feet (8,500 m). However, finance was very tight and no action was taken until 1930s, when the specification was enhanced to a 28 pounds (13 kg) shell, 3,000 feet per second (910 m/s) muzzle velocity, a 35,000 feet (11,000 m) ceiling, a towed road speed of 25 miles per hour (40 km/h), maximum weight of 8 tons and an into action time of 15 minutes.
In 1934 Vickers Armstrong produced a mock-up and proceeded to develop prototypes of the weapon, which was selected and passed acceptance tests in 1936.[5][6] However, the weight specification was exceeded and the muzzle velocity not achieved. Furthermore, the initial mechanical time fuze, No 206, was still some years from production so the igniferous No 199 had to be used, and its lesser running time limited the effective ceiling. Gun production started the following year.History
BackgroundField and Anti-tankLike other British guns the 3.7 had a secondary anti-tank role, this meant that if the gun position came under tank attack it would engage the tanks. However, during the campaign in North Africa the shortage of capable anti-tank guns led to some agitation to use the 3.7 in a primary anti-tank role, i.e. deployed specifically for anti-tank defence.
Guns did have their sighting arrangements improved to enable better anti-tank shooting. However, 3.7" was only used in the anti-tank role in one or two emergencies. The arrival of the smaller 3-inch calibre 17-pdr anti-tank gun in late 1942 made a primary anti-tank role irrelevant for the 3.7" but if, unusually, they were deployed in a forward area then they could have a secondary anti-tank role.
The guns were used in the field artillery role quite extensively in the second half of the war in Italy, NW Europe, Burma and the SW Pacific. Batteries were issued with the necessary fire control equipment. Counter-battery or counter-mortar fire was the usual role. However, their HE ammunition seems to have always been fuzed for airburst; this means maximum ranges were limited to 9,200 yards with No 199 fuze and 16,200 yards with No 208.
The 3.7" gun was also used to arm the Tortoise assault tank, where it was designated the Ordnance QF 32 pounder. The Tortoise, which is best described as a self-propelled gun, never saw service.