The following is not in regards to the OPs find... If he can get his hands on a caliper and/or grain scale I'd be more than happy to help ID what he has. I.cutler - Please DO NOT use "material" to rule something out of being identified as a round ball. That logic can only be applied loosely to Minies and other "conical shot". Depending on the times, country, and individual, round balls were made of VARIOUS conglomerates. Instead, use measurement, weight, and "vicinity likelihood" as a basis. "Larger"? - no, not necessarily. There were plenty of smaller caliber pistol balls, and the US used buck-and-ball loads almost exclusively in certain long arm models for more than two decades in various regions... Case and point, from my personal collection - Mexican BRONZE musket shot found In the vicinity of the La Bahia massacre. The French, from which Michigan (OPs location) derives it's name from.... supplied a lot of the local inhabitants (Indians) with firearms during the Seven Years War. Indians would commonly use trade ingots and scrap (lead/iron/bronze) to manufacture shot for their muskets. I'm not saying the OP did/didn't find a round ball. I'm simply trying to show that there is more to take into account. You don't want to just chuck that into the trashcan assuming it's a rusty ball bearing!