Hypersensitivity of Old Deteriorated Explosives

Lead azide was a common ingredient in primers and fuses from the time of the Civil War and most certainly can be encountered in older burial sites. When lead azide is encased in a copper container (primer cap, percussion cap, or blasting cap) and water gets into the container, copper azide, a hypersensitive compound, can form. Some Civil War rounds (i.e., the Schenkel) contained a musket cap inside the round with an inertia-driven slide hammer to detonate the round on impact. All musket caps used in the Civil War were made of copper and some had lead azide. 

The Bluejackets Manual (US Navy, 1940) states, Powder stored for a considerable period in a leaky container is likely to deteriorate rapidly, with the attendant danger of spontaneous combustion. Because Navy bag powder contained smokeless powder with a charge of black powder at the end placed next to the primer, it is not known whether this comment referred to either or both types of powder. However, the Manual continues Smokeless powder which has been wet from any cause whatever must be regarded as dangerous for dry storage.  

War Department Technical Manual TM 9-1904, Ammunition Inspection Guide (March 2, 1944) states, 

The dangerous nature of explosives makes safety the major consideration in their destruction. They are made immeasurably more dangerous by deterioration because the sensitivity of such 

both an Army and a Navy manual suggest that at least two types of explosives likely to be encountered become hypersensitive or may even combust spontaneously. 

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