From the attached press release: "Fastest-firing single-barrel cannon, the M39 revolver-type weapon, is fed a ribbon of 20 mm ammunition by Grant Wantling, associate engineer at Armour Research... Show moreFrom the attached press release: "Fastest-firing single-barrel cannon, the M39 revolver-type weapon, is fed a ribbon of 20 mm ammunition by Grant Wantling, associate engineer at Armour Research Foundation of Illinois Institute of Technology. The cannon, currently used on jet warplanes, is the result of eight years intensive research by ARF, the government, and industrial concerns." Photographer unknown. Date of photograph unknown. Date range listed is approximate. Show less