Having the same approximate hardness, which one would you prefer and why?
S.
What type of firearm are they for?
If pistol what caliber?
How fast are you going to be pushing them?
There are a lot of questions but for general rifle hardball will work and will work for most pistols as well.
But some because of speed don't need the real hard stuff.
They will both work.
If you have some softer lead to mix with it the bullets will perform better.
Go for it and have fun,just make sure the size is right for your rifle pistol or you might have some leading problems.
I use the hardball to cast Lyman 525 wad slugs....you can just about shoot them into a dirt backstop and dig them out and load them again.......My son calls them "Superman killers"....LOL