As the others said, they will certainly be safe, but likely won't produce much in the way of accuracy, unless they are soft enough and pushed with enough pressure to obturate, or bump up to bore dia. If leading is a problem, you can tumble lube them with Lee tumble lube. If various load tests don't result in satisfactory results, melt em down and cast them into something you like
Bullet casters are the best recyclers.