No disrespect to my brother VMI Digger, but before you go the brush route, let it dry out VERY thoroughly and take a wooden toothpick to it. You might can "flake off" some of the extra-dry corrosion and find nice smooth brass beneath - like toothpicking a button. It has to be BONE dry for this to work. If that doesn't work, I'd try a little naval jelly, and resort to the brush if all else fails (VMI pointed out BRASS brush and I agree). But in all honesty, if the first two methods don't work, it's unlikely you have enough metal there to see a date. We don't see naval shells in my neck of the woods, so SUPER fuse. I'm going to PM you before I head your way the first week in August . . .