I have done this before when making cast bullets take a production cast bullet that works in your firearm... put the production bullet and your bullet in a vice and crank it down if they both deform at the same rate they are about the same hardness. First time after water quenching my bullets my bullet didnt deform at all the production one crushed so that led me to belive my bullets where to hard that why they where leading up the barrel badly. So I didnt quench them put them in the vice again and volia about the same hardness as a production bullet.