What is ss deck gun ammo and what are the differences between the ammo types?

[RoaldLarsen]

Originally Posted by Sailor Steve

Destroyer guns of the period had Common rounds and nothing else, and carried the wonderfully awkward designation of SAPCBC (Semi-Armour-Piercing Capped British Common).

Ah - a terminology ambiguity, wrt the 'BC' suffix. The later term APCBC stood for Armour-Piercing, Capped, Ballistic Cap.