Gunners on airplanes determine how much ammunition they have left by glancing at dials of a new electrical indicator installed in the instrument panel. As the guns are fired, electric impulses turn down the dials regardless of where the guns are located in the plane. One of the instruments has four dials which show the amount of ammunition remaining for two thirty-caliber and two fifty-caliber guns, the former holding 500 rounds each and the latter 200, making a total of 1,400 rounds.