Snaps asked:
> "You'd think they would have blackened in a fire pit?"
Looks like you've got some fire-melted civl war bullets. Lead doesn't "blacken," even in a fire. However, when in molten form it can trap black ashes and small bits of charcoal. BUT... if the melted lead cooled back to solid form before the red-hot coals turned to ash, nothing gets trapped in the lead. See the photo below for an example.
My thanks go to Parsonwalker for the well-focused closeup photo of the firemelted 3-groove Minie bullet he dug.