Armour-piercing discarding sabot

Armour-piercing discarding sabot (APDS) is a type of kinetic energy projectile fired from a gun to attack armoured targets. APDS rounds are sabot rounds and were commonly used in large calibre tank guns, but have now been superseded by armour-piercing, fin-stabilised, discarding sabot (APFSDS) projectiles in such guns. However, APDS rounds are still commonly used in small or medium calibre weapon systems. For a given calibre, this type of ammunition can effectively double the armour penetration of a gun, compared to those firing armour-piercing (AP), armour-piercing, capped (APC), or armour-piercing, capped, ballistic capped (APCBC) projectiles. The saboted light armour penetrator (SLAP) concept applies this technology to small arms calibres.

APDS was developed by engineers working for the French Edgar Brandt company, and was fielded in two calibers (75 mm/57 mm for the Mle1897/33 75 mm anti-tank cannon, 37 mm/25 mm for several 37 mm gun types) just before the French-German armistice of 1940. The Edgar Brandt engineers, having been evacuated to the United Kingdom, joined ongoing APDS development efforts there, culminating in significant improvements to the concept and its realisation.The APDS projectile type was further developed in the United Kingdom between 1941–1944 by Permutter and Coppock, two designers with the Armaments Research Department. In mid-1944 the APDS projectile was first introduced into service for the UK's QF 6 pounder anti-tank gun and later in September 1944 for the QF 17 pounder anti-tank gun.

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