My mom and dads neighbors have two black labs. They are the two dumbest most aggressive, poor tempered dogs I think they've ever had. If thay can even hear you they are barking and snarling.
How is that relevant to the topic at hand? Dogs that aren't properly trained and socialized can become aggressive and poor tempered. That can happen to any breed of dog though some breeds are more prone to that than others. Labs (from personal experience) are not as prone to this as other breeds but as I said before lack of proper training and socializing can (and most of the time does) lead to this.
Anyway now to the point of the thread:
I've trained many a hunting dog (labs and other flushing retrievers) and while my dogs and the dogs I train are exposed to gun fire on a daily basis you need to keep in mind that the gun fire is not continuous fire nor is it hundreds of rounds at a time. Typically we're looking at 10-20 rounds AT MOST (usually its more like 5-10 rounds) per dog per day that they're exposed to. Even then most of that is fired at a distance from the dog (anywhere from 50 to 500 yards).
If you fire a lot around your dog he/she will lose their hearing just like you would without hearing protection. A dog that is deaf will be less likely to hear you or others coming and while your dog may not be aggressive naturally a dog that is surprised because you came up from behind and he/she didn't know you were there might just snap at you at first simply because they were surprised.
All that aside if you've got hunting dogs you want to be able to communicate with them and the easiest way to do that is via their hearing. If your dog can't hear you because of hearing loss you will have lost your long distance recall of the dog as well as any chance for you to get his/her attention.
In short the answer is no don't shoot a lot around your dogs - especially with hunting rifles, ARs, AKs and service caliber handguns.