re: Gun Shy Lab

Imo tying a dog up to endure the "blast" is the worst thing you can do.
There is a proper introduction that you should do with your dog and it should never be right near him.
You need to start 200yds away popping off .22 blanks having someone that is about 100yds away throwing bumpers after the shot. You slowly bring the .22 blank shooter in to 150-100 yds after at least a week of this.
You then migrate closer as the weeks continue.
When comfortable you only then begin to progress doing the same thing with shotgun blanks.