It look's a little thick Griz.....But the diameter is just about right for a 12 pounder.Check out Harry Ridgeway's site....reilcman.com in the artillery section.Nice find's Happy Holiday's to You and Your's!!!!
Do you see any dimples where the ball would have sat? Here is a pick of one that I tryed to make a little bigger. I do know there was 2 or 3 different sized plates for canister. Nice finds,Jonathon.