The M39 A2 and A3 are gas operated, electrically primed revolver type cannon. They fire the M50 series belted ammunition with disintegrating links. The complete cannon assembly is contained in a steel welded cradle unit which incorporates aircraft mounting points at the front barrel entry position and cradle rear. They can be mounted in any position on the longitudinal axis to suit specific aircraft requirements and be fed from the right or left hand side.