Musketball and lead ingot?

[Kasper1212]

I think this might be a musket ball, its 10mm, but I've never found one before so i'm not sure....I also found this small item, I believe it could be a lead ingot to make the balls, it' super heavy and not very big....but it has letters I cant make out on the back...any help to identify would be appreciated. I don't have scales or calipers. Thanks!

 

[nwpa]

Looks like a lead round ball would be around .390" so 40 caliber, just a guess on the lead bar could be plumbers lead and looks like a possible F X 1 stamped on it.