I cut this out of the rules:
4.1 Cast Bullet - A projectile made of lead or lead alloy which has received its basic form by being cast of molten metal in a mold rather than being formed in a die. Except in the Plain Base Bullet class, a gas check having a sidewall height of no more than 0.10" may be attached to the base. Enlarging or reducing a cast bullet by bumping or swaging is permitted
Powder coating a bullet isn't a gas check so I'm wondering how it relates to bullet eligibility.