Years ago . . . Well the 70s- early80s
I was talking to and older farmer (in his 60s-70s) near Spring Hill TN and he told of finding a pile of boolits and a big piece of solidified lead on the family farm when he was a kid. They were Minie balls so he figured they had been cast somewhere around the time of the Battle of Franklin. He also guessed that they were told to saddle up/ get ready and had just dumped what lead the RCBS pot still had in it and were too busy to cart off the Minies and lead when they left.
I use 1/2 of a 10 gallon water heater tank and engulf the entire thing in a small bonfire. Come back in 1/2-1 hour and a bunch of molten lead under the sawdust/carbon bed and a bed of coals to keep it molten even though that much mass keeps its heat for a while. It is a cold weather project.
I was gonna use a propane tank but all the "Meth Labs" in the area had them in use!!