My post above shows the stats on tin/lead mix, ie: 50/50 used to be known as plumber's solder.
I still have a couple bars of that for adding to my lead mixes.
The x-ray room wall sheet lead I have is too pure and needs 1/2" of 50/50 added to a 20 pound pot for reduced dross developement and improved casting properties. This does not appreciably harden the pure lead, at least nothing measurable.