Hey Bob. I seem to recall reading that 10:1 gives you the hardest tin/lead mix. Further adding antimony will increase hardness.

Antimony/lead (the old clamp-on wheel weights) mixes cast smaller than tin/lead, I think.

In my 14 bore rifle, the difference between soft lead and WW is about .002" - that is all.

The higher the temp with antimony alloys, the more frosted the bullets and theoretically, the smaller the projectile, but I cannot measure the difference with my calipers, but the micrometer, which you can measure to .0001", ie: 1 10 thousandths might see a difference. Indeed, you can measure to close to 1/2 that, as in between the marks. I have never measured them with the mic. as I do not see measurements that small as being useful.
A cooler "melt" will give smaller projectiles, but would be difficult as far as consistency is concerned.

I thought the WAA12R wad was THE wad for the Lyman sabot slugs, especially when using slower powders like Longshot and Steel. I had the data for that around here and cannot find it now.