If you have good genetics/traits to start with and dog came from hunting family, you shouldn't have to break a dog to a gun going off. Just get it use to loud noises like bagging two pots together and give it something to take interest in. I've had good GSP and GSP/setter crosses didn't have to go through gun banging to break them in.
Now I run coyote hounds (running Walkers) and teach them just basic commands like you do a bird dog and the hunting part just comes naturally. One thing I had to keep in mind is where I get my dogs from when I first started as some are gun broke from birth and some crosses are not. The dogs are bred to run and catch, and others bred to just run and bay up, so you pick the cross that fits your style of hunting. You need to get a dog use to gun fire then put something of interest in front of it and just shoot dam gun that's quickest way, and after you shoot give dog lots of praise if it doesn't run. If it runs, then use a leash when shooting and still give praise after. A dog needs to learn you are there to cover its back to anything new.
