Concussions occur when the head is accelerated or decelerated so rapidly that the brain actually strikes the inside of the skull. Therefore, anything that you can do to minimize the amount and speedyour head is displaced when you shoot your gun might reduce the risk of further concussions. In addition to a heavy semi-auto shotgun, maybe you would want to consider a neck brace or exercises to strenghten your neck muscles so that your head is not pushed as far back and up when you shoot.

Also, you may want to avoid hunting alone. As you have noted, becuase of your past history of concussions your risk of a future one is high no matter what precautions you take. It could be dangerous if you are in the woods by yourself and you fired a shot, suffered a concussion and became disoriented. I suffered a stroke last year and my wife no longer lets me go hunting by myself out of fear it could happen again and I would be stranded in the woods.

Caldoc