Sidebar: earlier this year a Facebook post from the UK was subject of much commentary both sides of the Atlantic. The Brit chap who unearthed a rusty .50 cal. cartridge in his garden was worried that it would explode (or something) and sought advice. Fellow Brits informed him that the law/regs/whatever required him to notify The Authorities who would come remove the thing in the name of public safety. Or something. Which apparently is what happened. (Illegal possession of an "explosive device" was cited.) Yanks of course said "We'd just pick it up, rub it off and put it on the shelf." Concern about spontaneous ignition were dismissed by competent observers who noted (correctly) that a cartridge cannot fire without detonating the primer (if functional) and that in the vastly unlikely event of an uncommanded ignition the result would be a low-order detonation in the atmosphere rather than higher pressure in a firearm's chamber. Now, discovery of a UXB, let alone the Tallboy in Frankfurt (?), is a whole nuther matter...