A
shell is a payload-carrying
projectile which, as opposed to
shot, contains an explosive or other filling, though modern usage sometimes includes large solid projectiles properly termed
shot (AP, APCR, APCNR, APDS, APFSDS and proof shot). Solid shot may contain a pyrotechnic compound if a
tracer or spotting charge is used. Originally it was called a "bombshell", but "shell" has come to be unambiguous in a military context.