Boats, if that block of lead was in my backyard, here's what I would do:
* Jack up a side of the block with a hydraulic jack
* Cut long section spaces to preclude the heat sink issue with the sawzall starting on the bottom
* Buy aluminum gutter pieces (the widest you can purchase) the length of the block
* Buy this torch and many propane tanks, you'll need them
... might want to ask a gas dealer to rent one of the big propane tanks
(You need to Login or Register to view media files and links) The 3000 degree torch does an quick excellent job melting scrap lead I get at the scrap yards
* Melt the cut sections into the gutters
* Then sawzall the smaller blocks from the gutter and start stacking them up
Hmmm - 5000 lbs is approximately 175,000 bullets weighing 200 grs! Happy casting or selling!