Remember folks, the ideal is to have a tin to antimony ratio of 1:1. Ideally in the 4-5% range.
/\ This pretty much is the famous Lyman Alloy No. 2, the standard bullet casting alloy that Lee specifies for use with its molds to drop the advertise diameter and weight.
For daily shooting, Lyman No. 2 can be expensive, if you can even find it or are able to find sufficient amounts of tin and antimony to mix with COWW or pure lead.
I have a small stash of lino and have been using it sparingly to sweeten pure lead, or to mix with lead of questionable alloy.
Pure COWW doesn't cast well-enough for me and I mix lino in 1:6 ratio (linotype to COWW) to come up with a very nice alloy that casts very close to Lee spec diameter and weight. For example, my .45 (ACP) Round Nose bullets drop at .452 so I don't have to resize anymore. As well, 1:6 alloy gives beautiful, well filled out, shiny and smooth bullets.
Since I dont have the equipment (who does?) to determine alloy percentages, I just test batches by molding a few bullets to check diameter and weight, and see how well the mold fills out, ie, sharp shoulders and in the case of Tumble Lube style bullets, the mini grooves fill out to correct diameter.