Found this in the same area where the battle of Monguagon took place in 1812. It is heavy and has a small flat area on it. I am wondering what you guys think, would you think this is a muskett ball?
If the measurement is correct, then it's probably a ball, "bullet" for the British Brown Bess musket from the Revolution or before. They were .72 caliber or so, which relates to just about 3/4 inch, which would be .75 caliber. The French musket fired a .69m caliber ball.
Just speaking up in confirmation of what BosnMate said ...and adding a small correction. Based on the slight impact-damage to the lead ball, and its apparent size based on the ruler in the photo, the object you found appears to be a fired musketball from the .75-caliber "Brown Bess" British musket. http://en.wikipedia.org/wiki/Brown_Bess
Actual ball diameter for that musket was typically .71 ...but "dug lead" patina can increase it to .72-inch.