shell

A shell is a projectile, which, as opposed to a bullet, contains an explosive or other filling, though modern usage includes large solid projectiles previously 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. Shells are usually large rounds fired by artillery, armored fighting vehicles (including tanks), and warships. Shells usually have the shape of a cylinder topped by an ogive-shaped nose for good aerodynamic performance, possibly with a tapering base; but some specialised types are quite different. The most common shell type is high explosive, commonly referred to simply as HE. They have a strong steel case, a bursting charge, and a fuze. The fuze detonates the bursting charge which shatters the case and scatters hot, sharp fragments of steel (shrapnel) at high velocity. Most of the damage is caused by shrapnel rather than by the blast. Depending on the type of fuze used the HE shell can be set to burst on the ground, in the air above the ground, or after penetrating a short distance into the ground (either to transmit more ground shock to covered positions, or to reduce the spread of fragments).