(March 2010) Enlarge Requa "Eureka" Battery Gun Wheels - Billinghurst and Requa, a company experimenting with rapid fire weapons, produced this sensational salvo gun. It fired twenty-five barrels at once in a deadly volley, used for protection of bridges and passes, or against closely packed enemy troops. It was of .52 caliber and all barrels fired at one pull of the lanyard. At first it used paper ammunition but later used metallic cartridges set into a perforated metal strip. These strips were preloaded and inserted into the barrels and fired with one pull of the lanyard. It was simple in design, reliable (especially with the metallic cartridges), and heartily dreaded by the enemy. These are the wheels from one of the Battery Guns pictured with a Defensive Mortar