Those bullets were 14 BHn. Heat treated I expect 18-20 BHn.
With the pressures that load developed the fact the bullets didn't strip is amazing. The alloy was like putty but held the rifling somehow.
This alloy is a mix of old bullets I had kicking around. I would say it is close to WW plus a little tin. Air cools to right about WW plus tin so I figure it will heat treat in a similar manner. I have close to 100 pounds of the mix so I can do a bit of shooting.Also don't forget that a diluted alloy HT'd to the maximum bhn isn't the same thing as a more rich alloy HT'd and then annealed to the same number, or more mildly HT'd to the same number.