Just melt it down outside, pour it and move on. I used many Lbs of that stuff back in the '60s. Lived around Petersburg Va. and you could not dig a hole with out finding bullets. It all was cast into .58 Mini's for an original 1863 Springfield that I bought for 50 bucks with my paper money. It went Everywhere with me, in 1959 at 12, I was the youngest member of the NSSA and shot the rifle, was at the first shoot at Ft Shenandoah and many after.
Hung out with a couple older guys who had metal detectors and had a box full of Minis and slag. Once I got a metal detector I would sell a big Coffee cans full of them to a dealer for 25 bucks. I literately had Tons of stuff, Shells, Balls, Buttons, Belt buckles, Breast plates, canteens, bayonets, you name it I probably had it.
Got a little carried away here.
Tim C.