I am not sure there is a lead free and true workable, affordable substitute for lead. Part of an article I read said..........

( "gun advocates strongly oppose banning lead bullets throughout California, saying it is a slippery slope that would lead to gun controls and end hunting in the Golden State.
They argue that hunters who abandon lead and turn to harder bullets such as copper or tungsten could technically be in violation of federal regulations barring armor piercing ammunition".)

I personally other than steel shot, have not used any type of substitute But a friend of mine who tried using solid copper rounds on a wild goat hunt said he could not knock one down very well as the solid loads did not expand and did very little damage.