Not knowing the tin content of any smelted lead was always a problem so Started of with a small amount of tin and worked it up until I got the results I wanted.

It was hit and miss and time consuming so I started doing a drop test.

I put a bullet of known hardness at the bottom of a tube and dropped a weight on it and then measured it with a micrometer. When I was casting I would do a few and do a drop test on a couple and did this until I had a similar hardness to the one I was using as the example.