POR-15 : Yes
Rust bullet: No.
The POR-15 product is excellent and does all it claims. The key to a good finish is good preparation. Remove all rust , grease , silicon polish etc back to bare metal. Follow the makers instructions.
Rust Bullets? Not exactly sure if these are the sacrificial anode type products which come onto the market from time to time.
If so then have a browse through the archive for definitive information. Simply put: Save your money and put it toward something useful for your car.
Pete.