Editing Shell (projectile) (section)

==Unexploded shells==
{{Main|Unexploded ordnance}}
{{unreferenced section|date=September 2023}}
The [[Artillery fuze|fuze]] of a shell has to keep the shell safe from accidental functioning during storage, due to (possibly) rough handling, fire, etc. It also has to survive the violent launch through the barrel, then reliably function at the appropriate moment. To do this it has a number of arming mechanisms which are successively enabled under the influence of the firing sequence.

[[File:Irakian corroded shell.jpg|right|thumb|Corroded but live Iraqi [[artillery]] shell dating from the [[Gulf War]] (1990–1991)]]
Sometimes, one or more of these arming mechanisms fail, resulting in a projectile that is unable to detonate. More worrying (and potentially far more hazardous) are fully armed shells on which the fuze fails to initiate the HE firing. This may be due to a shallow trajectory of fire, low-velocity firing or soft impact conditions. Whatever the reason for failure, such a shell is called a ''blind'' or ''unexploded ordnance ([[UXO]])'' (the older term, "dud", is discouraged because it implies that the shell ''cannot'' detonate.) Blind shells often litter old battlefields; depending on the impact velocity, they may be buried some distance into the earth, all the while remaining potentially hazardous. For example, antitank ammunition with a piezoelectric fuze can be detonated by relatively light impact to the piezoelectric element, and others, depending on the type of fuze used, can be detonated by even a small movement. The battlefields of the First World War still claim casualties today from leftover munitions. Modern electrical and mechanical fuzes are highly reliable: if they do not arm correctly, they keep the initiation train out of line or (if electrical in nature) discharge any stored electrical energy.