Last time at Fort Sill, OK they were still finding pre-WWI cannon projectiles and detonating in place. At the time I thought they sure did use a big bang to set off the old bang. After I learned about explosives, I realized that is what is known as a secondary explosion.

Here in DFW there have been several neighborhoods that were bought back by developers and the government after residents found 250 and 500 pound aircraft bombs from WWII training. According to the folks I met from a sub-contract EOD type company the explosives decompose back to almost straight NitroGlycerin.

At Camp Gruber OK I personally found several UXO 4.2" mortar rounds after I hit a bump in the off road track I was driving on. When the gun truck behind me got on the radio to stop and see what I had hit, I thought uh-oh, someone's pet got on post. After I saw the UXO, I almost needed new pants, and the day off.