This meant a system that used a blank firing replica gun, and a system to detect blank rounds being fired. Very cool, and the way he went about it includes some interesting electronics.

A number of blank-firing guns have been handed in to Derbyshire Police during an amnesty this month. The force said it had ...

More than 40 guns which fire blanks and hundreds of rounds ... taken part in the amnesty with the aim of removing 'top ...