I was stationed at Ft. Devens in 1971-72, so I don't remember a lot of cannons with or without crests. But there were quite a few that folks brought out for the celebration of Patriot's Day when we re-enacted the march from Acton (Cpt Davis' home) to the bridge between Lexinton and Concord.
I'm sure that there is SOMEONE here that has more up-to-date info.