If you’re worried about gun shyness, get a cheap toy cap pistol. Use it at a distance when the pup is playing, eating, drinking, doing fun things in general. Use it at random times until the dog ignores it. Then get closer. Eventually move to blanks and finally the real thing. Always pay attention to the dog, they will tell you what you need to know. Also, have your girlfriend help by giving treats when shooting early on. Creates a reward response to gun fire that can be carried over to training.