I think its probably for the Brown Bess based on the size. I see your from NY so if you dug them in that state, there was a ton of Rev War activity there. It help some.
I hit this spot along the James River here in Virginia several years ago and dug a bewildering array of cast round balls up to 80 caliber. Some were crazy field cast with both sides of the ball being offset due to a bad hinge pin in the bullet mold. Even smaller caliber balls with the cast sprues still attached. I'm talking 40 caliber balls on up to the 80 cal. Those extremely large balls had me pretty perplexed. I figure they were for very large bore imported flintlock.
I think you're on the money and they're rev war balls.
Pretty sweet!