Once you have detected a hit you should call one of the damage functions provided. You can do it in two forms, detect the hit on the Pawn and then using the HitActor (the bullet) as the instigator of the damage and the current blueprint (your Pawn) as the receiver, or detecting the hit on the bullet and using the HitActor (your Pawn or any other Actor) as the receiver and the current Blueprint (your Bullet) as the Instigator.