My alloy mix tests at 14-15 bhn. With this alloy i've fired 30-30's that chrono @ 21-22 K fps, about the same fps that i'm planning on for the 223. I believe that sealing the bore is of prime importance, more so than hardness. I did mix a pound of 7 1/2 shot with the last 20# pot and water droped bullets but I did not get the results that others get. We'll work with what we have for now.