BC of a lead ball is dependant on (and proportional to) the caliber.... For a .25 cal, it is 0.035, roughly the same or slightly less than the BC for a JSB King.... In .22 cal, the BC for a lead sphere is 0.030, which puts it about the same as a 15.9 gr. JSB Exact Jumbo and less than the 18.1 gr. Heavy....Bob