I have seen actual gunshyness cured by diligent work involving lots of birds (expensive) and lots of time (precious). I have also seen more than a few dogs that had no problem with gunshyness absolutely ruined by being left outside on the Fourth of July. I don't mean to be be the bearer of bad news, and others may have had a totally different experience than me, but I have never seen a dog cured of gunshyness caused by prolonged exposure to fireworks. I am only letting you know my experience so you can make an evaluation of your still-young dog, and make a decision based on the amount of time and money spent to try and affect a cure, and what you want that dog to do for you.

Good Dogwork and Good Hunting