You did the number 1 thing that creates a gun-shy dog. Using the "Let's See What Happens" method just created a ton of work for yourself. And now you want help undoing what you've done.... Now you have to condition your dog to associate loud noises with something rewarding like treats or food or play. This topic has been covered on here many times. Be patient and do what you should have done in the first place, realize it will probably tale you 2 or maybe 3 times as long now to condition your dog to loud noises without apprehension. All I can say is good luck!