The problem with getting rid of lead ammunition from a hunting perspective is also that lead is simply more effective for one shot kills. With lead being somewhat soft it expands on impact, causing a larger wound channel and thus more damage, increasing the chance of dropping the animal easily. To my knowledge there is no other easily available metal with the same characteristics. In addition, some states and groups are moving to ban bullets made of copper or steel on the basis that they are "armor piercing", due to the fact that they don't expand like lead does and thus retain energy and penetrating power through a target.
What You Need To Know About a Federal Gun Buyback