Upidy;if you are talking about the dog is gun shy,it will be a hard battle and time consuming.
the glues you speak of,I don' t know what that is.

I had a liver pyded pointer that was gun shy.I got it to not go back to the truck after the first shot,it took two years.you need a starting pistol if you live in town.

do not put a feeder into the pen,feed the dog your slef each day.while he is eating fire the pistol from behind the house(a long way off)but close enough for him to hear it good.do this every day while eating getting close and closer.not to close at each shot.like the same spot for a week then a few yards closer for a week and so on.if the dog shys away back up a little.remove the foor till the next day.

like I said it takes a long time.just don' t make him run each time.be slow and patiance with him.if he doesn' t shy prase him a lot and give a treat he really likes.

good luck with the work.