old see the church key (hole punched in the can by an " opener" ) style of opening ? and the fact its a seamed can -- thus its 1950's or earlier ----(maybe part of 1950's a bomb shealter survival kits or WW2 war ration stuff) -- ah ha !!!-- according to the website "olive drab" your can is WW2 era *** theres even a "photo" of a can just like it . solved !