Good idea Dave. How I do it:
Take dog out of truck and start playing ball. Have buddy 500 yards away and start shooting once every minutue.
Keep playing ball (or whatever the dog likes if it isn't ball).
Have buddy move closer and closer until he is with you.
I was given this advice by my great grandfather who raised shorthairs for hunting.
It has not let me down. I've done this with three labs and none were gunshy afer that.
Putting them in a blind and firing over their head is about the worst thing when they haven't been exposed to it.
Props to Dogfish who helped me break in current dog Chase.