Wildlife conservationists are facing off against the gun lobby over hunters’ use of lead bullets.

This month, the National Rife Association (NRA) announced a new campaign to discourage regulators and lawmakers from limiting the use of lead bullets, which birds like eagles and vultures sometimes eat by accident and then contract lead poisoning.

The gun group calls the effort to regulate the bullets, as California is currently considering, an “assault on traditional lead ammunition” that is based in bad science.

Conservationists looking to protect the birds have fired back.