I once bought all the lead shielding out of a doctor's office that was being converted to an apartment building. The whole X-Ray room had been lined with the stuff and it had only been in there about a year. I gave 10 cents a pound for the stuff back when lead was selling for 50 to 60 cents a pound. The guy who sold it to me estimated that there was 500 pounds of it, and so that's what I paid him for. When I weighed it out there was around 800 pounds of it, you do the math.
I have to add shot and/or tin to it to harden it up some because it was dead soft lead sheeting, just what I wanted for my muzzleloaders. I am not as precise as Daryl, I just throw in a small handful of reclaimed shot to every 10 pound batch of melted lead, it seems to work for me. And yes, they will harden up, especially if dropped right into a bucket of cold water. I use a plastic bucket and have had no problems with one dropped bullet damaging any of the others. I roll them in Alox and let them dry overnight.