U.S. 37mm Anti Tank Rounds for the M3 AT Gun - WWII

37mm HE and AP 37mm Canister 37mm HE M63 Shell - 37mm APC-T M51Shot - 37mm M2 Canister

The M3 Anti Tank Gun was essentially a copy of the German PAK 36 with minor modifications. By 1942 that caliber was obsolete for use against modern armor. While the U.S. had started introducing 57mm guns in an attempt to modernize, the Germans already were moving beyond the 75mm class in their attempts to keep up with the Soviet tank threat on the Eastern Front. Tank/Anti Tank weaponry developed at a fierce pace during the war.

(Image Re-Posted with Permission)

AntiTank Gun M3 U.S.Training Chart

German 3.7cm PAK 36
German PAK36 U.S. HE and APC-T Projectiles
M63 HE "Shell"  - M51 APC "Shot"
U.S. M3 Rounds compared to German PAK 36 37mm AT Rounds - U.S. & German

M63 HE Shell was almost completely filled with explosive and had a base-detonating impact fuze.
M51 APC-T Shot had a tracer element pressed into the base of the solid projectile.
APC ("Armor Piercing Capped") shot consists of three parts: a solid penetrator with a piercing cap, topped by a ballistic cap. The reason for these parts is, at high velocity, the hard steel penetrator would shatter against faced armor. If tipped with a soft steel piercing cap the impact shock is reduced keeping the round intact. The hollow aluminum ballistic cap on top, provides a better aerodynamic profile.
Note that the German AP round (far right) is un-capped. Its slower muzzle velocity (2500 fps vs 2900 fps) did not require it.  (See 75mm Tank page)
M2 Canister is for close quarter defense against massed infantry. The projectile is filled with shrapnel and bursts open as soon as it leaves the muzzle. The effect is that of a large shotgun.

U.S. 37mm "SPAT"

American tactics for anti tank warfare were about speed and maneuver. Rather than using fixed emplacements waiting for the battle to come to them, mobility was preferred to bring the fight to the enemy. Towards that end, the U.S. was fond of the S.P.A.T., "Self Propelled Anti Tank".
Shown is the 37mm M3 mounted on a Dodge three-quarter ton truck (circa 1943).

My other related pages....
Russian 45mm
German PAK36