Pussers British Navy Gunpowder Proof Rum 700ml is a traditional Royal Navy style rum produced at original Admiralty strength and in accordance with the Admiralty’s blending recipe last used when the Royal Navy discontinued its daily ration on 31 July 1970. Gunpowder Proof Rum Prior to the invention of the hydrometer, the Royal Navy ship’s “Pusser” shutdown claims of watering down sailors’ daily tots by dousing a bit of gunpowder in the rum and attempting to light. If the mixture ignited, the rum was “at proof.” If it didn’t, the Pusser might find himself tossed to sea.