A lock adapter for an ammunition can having a clamp lever with an aperture includes a rod element received through the aperture and mounted to a side of the can. The rod element incorporates a relieved portion on an end opposite the side of the can and has a length and diameter sized in combination with the relieved portion for clearance of the aperture through an angular displacement of the clamp lever for opening the can. A hole substantially perpendicular to an axis of the rod receives a padlock. A bolt received through a drilled hole in the side of the can engages a tapped bore in the rod. A Bellville washer is placed on the bolt between the side of the can and the head of the bolt. The Bellville washer includes a sealing gasket adjacent the side of the can to seal the bolt and bolt hole preventing moisture from entering the can.