I found this yesterday in Jefferson County, West Virginia in the lower (north) Shenandoah Valley. It was in a camp used by South Carolina, Virginia, Ohio, and Pennsylvania troops. It is .633 caliber, .882 in length and weighs 512 grains. As you can see it has a cavity that is sort of between plug and truncated cone. It is very similar to T&T 181b and Red Book page 242 #607. It seems to be for the Brunswick rifle, but I do not believe they were issued to the ANV.