Boy was Ron right
 

I cast some 500 gr .457" bullet for my Sharps replica using a 50/50 mix of wheel weights and pure lead. Ron, in a PM, told me that they would likely be still too hard for shooting out of a ML.
He wasn't lying. I shot them yesterday up at our camp. The brass was loaded with 70 gr (volume) of Goex FFg. I only fired a couple because I had the wrong insert n the front globe sight and couldn't see the target that well. But after going up to the target I noticed a couple bullet holes in the tree about 15 feet behind the target and before the embankment. I went over to examine it and fount that the 500 gr bullet passed completely through the center of a 10" red maple and embedded out of sight into another behind the first one with no sign of expansion. I did take a nice chunk out of the backside of the first tree.
This could be and elephant / dinosaur load out of the sharps!!!
I guess I have to soften it up even more. Maybe I'll only add 20% wheel weights instead of 50%.

You must have some wheel weight lead from before 15-20 years ago. The antimony in wheel weights now is around 3% if that. Years ago they had as much as 15% and were very hard. With you going 50-50 you should be bringing the antimony ratio down to just under 1.5% which would bring you in at 8-9 B at the most. If they are super hard after air cooling for just a couple of days then you have an exceptionally high amount of antimony. With a 95% lead, 3% antimony, and 2% tin it will take a good amount of time for them to air cool and harden up, week and a half to two weeks, but they will reach a pretty good hardness for that .45-70. Too hard will cause pretty severe leading because they aren't obturating and allowing gas to leak around the bullet at extreme temps. What those would be good for though is in a sabot out of a muzzleloader when going after something that could eat you. Obviously good penetration. I wouldn't shoot them out of that .45-70 anymore unless you want to deal with leading cleanup.

Yes HL I figured as much. I never thought they would be that hard. Looks like the ones I have left (not loaded) will be going back into the pot. with pure lead. I'll try them at about a 20% mix or maybe even 10%