If you are casting conicals you will need lead that is NO harder than 25-1 BHN. My best results so far are with pure virgin soft lead that I mix 250 gr of lead shot in per 5 pounds of pure lead. Some times I go as much as 500 gr per 5 pounds. You still end up with a soft product but it fills the moulds very well. On my Cabin tree tester I like the bullets to measure .030 to .038 the scale sent with the tester says dial reading .000 to .035 would be BHN 5,, 40-1 is .045 to .050 and BHN 8.5
I am thinking that my lead I am mixing is probably in the area of 6 or 7 BHN.
The problem with lead harder than 25-1 is the bullets get VERY hard to push down the barrel.You might do OK with getting the lead shot round balls down the barrel but the lead shot conicals are going to be very, very hard to get down. Also I got good groups with the lead shot bullets but I had to clean after every shot. if i used my soft lead mix I could shoot at least 5 to 7 shots with GOOD accuracy. Lead shot runs in the 12.5 BHN range. It is that same hardness as WW. For ML's keep it softer than 25-1
Ron