I have always had good success with making loud noises when I feed my pups. They associate the loud crack of 2 pans and later cap gun and then a blank gun to being a sign something good is going to happen. Do not rush into this. Your approach should be how do I condition my dog to loud noises instead of approaching it as let's see if he's gun shy. By putting a dog into any hunting scenario he isn't prepared for will often set you back in training and make it harder to correct something you didn't do right in the beginning