The law does not require only approved ammo, it suggests and lists approved ammo sources, but if all those sources do not work?... my understanding is if a ranger checks your ammo, and has any doubt, he will take a sample and have it tested. If it has any lead in it, you are sited after the fact. If not, then you are not.
The part about the law that is bothersome, is the possession part. I go out target shooting in the local woods all the time as the local gun range is cost prohibitive--and besides, shooting in the woods, is just more fun for me.... So if Mr Ranger has a good day, he hears me say I am target shooting, and smiles and says "good day to ya"... If he's havin a bad day, he takes my gun, takes my ammo and sites me for hunting with lead.
re: the modern all copper sabots by barnes... How poorly do they shoot out of a slow twist barrel? Are they even remotely accurate?
Axe