Well, it's is doable.
I pencil it out to be a 1.52 to 1; lead to tin ratio. That's a heck of a lot tin! What we consider to be hard bullets is 16:1 alloy and some folk will go as hard as 12:1. No one goes even close to 1.5:1.
Bullet hardness is what matters, not weight. Hardness increases with a decreasing ratio of Lead:Tin. However, it is a diminishing relationship such that little if any hardness is gained once you cross something like 12:1. If you want harder, you jump to antimony or something else (copper, silver, ...?). Tin is also very expensive relative to Lead. So that makes me think that something else is an issue here. I doubt that bullet is really 1.5:1 lead/tin and nothing else, but it is possible.
Well thank you for contributing to this, Brent. I think you were interested in the old historic paper patched bullet I pulled a couple months ago. It weighs the proper 228 grains (450-400 BPE), and Mike Rowe had said he expected it to be a 12:1 alloy. Well, I had an adjustable mold made, and the same length pure lead bullets come out at 278 grains, so I suspect like you that something else is at play. One thing I noticed when i went back and looked is the original bullet has the copper peg in the tip, which must displace 5-10 grains of lead weight. So the actual poured pure lead bullet is heavier than the original because of the solid nose. Still, if the original was 240 grains with the solid nose, we still have a disparity of 38 grains, which is hard to achieve with just tin alone.
