It's a lot of bullets if you're casting for .223 (63.6K at 55gr), but if you're casting for .45-70 (8642 at 405 gr), those bullets eat up your lead supply pretty quickly...
You can test for harness with a set of different hardness pencil leads. Lee also makes a device that you can buy. If you have a scanner for your computer, and a small diameter steel ball, and a scale, you can make the indention in an ingot with a known weight applied to it, scan the ingot at a high resolution, measure the diameter of the indentation, and then plug in the values to a formula that will give you the hardness. Since I have a scanner, stainless steel ball bearing, arbor press, and bathroom scale, that's the solution that I use.