With the help of my buddy, Harry Ridgeway (great guy!), I was able to identify this as a likely portion of a sabot from a Hotchkiss shell. It has James rifling, indicating that it was thrown from a 3.8 Hotchkiss.

This hunk of lead was unearthed by Mr. Ed Stotler, a digger who hunted Antietam and South Mountain. It was found on private property, with permission, and is part of a large bucket of iron frags and a few other artillery-related items. This particular relic was recovered from Antietam.

All firearms sold are pre-1898 and historic collectibles. They are not meant to be fired. Jim Stanley & Associates (cwartifax.com) will not be liable for injury incurred due to any weapon or artifact purchased from this site. All artillery projectiles sold by Jim Stanley & Associates are absolutely safe and have been professionally and safely de-activated.