A rifle shot is not the same blast as a shotgun discharge. I have seen dogs go gun shy because of the crack of a rifle. So I'd be careful about that.

Whining and crying with a shotgun blast is probably from the anticiaption of the retrieve which is a reward to the dog.
If the dog will no longer be quiet a bark collar can be tried but at a low setting to start with. The last thing you want to do is create more trama for the dog.

Or constant shooting of a blank pistol held and fired 20-30 yds back from the dog and at the same time a dead bird or dummy is launched at the shot, for the dog to RTV, while you handle the dog and teach it quiet. Once yo have the dog settled send it for the RTV. But only when you get it quieted down.
On sequences the dog performs correctly lots of praise for the dog and don't be real quick taking that bird or dummy from the dog.
I like to pet them talling them good boy for a bit and then reach for the item the dog is holding in its mouth.
Keep your sesssions short no more than 10 to 15 minutes but do several during the day. If the dog does it correctly - always stop on a high note or at some point the dog was successful - even if it is a slight improvement. Don't over do.

Through that constant positive repetition I would expect your dog to settle down and be quiet.

Or seek the help of a professional dog trainer - someone who will work with you and the dog and help teach you.

That would be my suggestion.
JW