A study of unexploded shells from the second world war has shown that one of the explosives they contain is becoming more sensitive to impacts. This explosive, called Amatol, is still in some of the ammunition being used during the Russian war in Ukraine. There is a widespread misconception that this unexploded ammunition is becoming less dangerous over time, says Geir P. Novik. The findings will change how he and his team handle unexploded ordnance.