A few suggestions

1) Patience is your number one key to success. Your puppy will still be a puppy for many months to come. Let him be a puppy. Sounds like you are having some fun and he's learning in the process. Just remember not to push anything. I have a dog that is nearly a year and a half old, but I still call him a pup, and I still let him be a pup some.

2) Fix that fear of noises, quick. You don't him scared of loud noise, plain and simple. When you feed him, clang things around and talk loudly (but nicely) and excitedly to him. Make noise with a metal feed pan, whatever. Just get him to like the noise. If you don't get him use to noise, I don't see how holding off until you fire a gun will fix anything, except that he will be a little more mature and sure of the world. That's another thing, win his trust. When he is a little bit older and sure of his surroundings and you, have someone walk off and shoota capgun some distance off while you are with the pup. You might encourage him, or possibly make no reaction at all to the noise. I can see both working. I don't think you need to do anything fancy to fix his shyness yet. Just let him be a pup, and I think he'll be fine. Good luck.