Musket Ball....?

[66Fairlane]

So I posted this earlier and surprised I hadn't gotten any ideas. When I first pulled it out I thought it was a musket. Once I got back in the house and started messing with it, I realized it was somewhat hollow. It was for the most part round but looks like half of it is gone. It is definitely lead. Any thoughts on what this could be?

 

[TNGUNS]

Nipple protector for percussion rifle

 

[s.c.shooter]

Possibly an old piece of buckshot or shotgun slug?