Panic buying led to a shortage which fueled the profits of the manufacturers of ammunition after Big Green, Remington Arms Company, went bankrupt from being the parent company of Bushmaster Arms, maker of the Armalite rifle used at the Sandy Hook School Massacre.
Except where mandated by federal law for hunting wildfowl and in the State of California in the range of endangered condors all shotgun, rimfire, and centerfire ammunition and all air gun pellets and all muzzleloader ammunition is lead.
The reason lead is used is lead averages a dollar a pound, and can be easily cast into shot and bullets (often copper clad) and lead is far denser than any affordable substitute, such as soft iron.
I’ve reloaded at least one hundred thousand shotshells, and thousands of pistol and rifle rounds, and I’ve cast a few lead sinkers and bullets.
We have a right to own and use firearms under the Second Amendment.
If tomorrow the government mandated non toxic projectiles then in a few years only the privileged class, lawyers and doctors and such, could afford to indulge the hobby.