Shotguns http://www.remington.com/products/firearms/shotguns/model-870/model-870-express.aspx Shotguns are an entirely different style of firearm.  In a shotgun there are roughly 3 types of rounds: bird-shot, buckshot, and slugs.  Each is different in its own way.  The bird-shot is multiple tiny bee bee's that, contrary to popular opinion, do not spread out to a massive area but stay relatively close.  Buckshot is a much larger but many less bee bee's.  Slugs are the most different of all.  Slugs are a solid piece of metal that is propelled out of the barrel at 1900 plus fps.  http://www.randywakeman.com/12vs20FederalBarnesTipped.jpg These slugs also have one of the fastest dropping trajectories of any gun.  Like most guns, the trajectory is an arc that starts from the muzzle.  In 25 yard increments the round rises and hits peak height, from the line of sight to the target, at 50 yards.  Both 20 and 12 gauge slugs are on target at 100 yards. Also, if we look at the wind drift of these slugs it is quite significant.  With a 10 mph cross wind, the slug moves three feet off course at 100 yards;  this is due to the design of the round.   Shotgun slugs are big, and round with a flat tip, unlike the rifle round which is designed greater distance and aerodynamics.  Do to the larger surface area, the wind has more of an effect on the path of shotgun slugs than rifle rounds.    http://www.woodburyoutfitters.com/v/vspfiles/photos/11623-2.jpg   The force produced by these firearms is incredible if you are not prepared.  By holding the shotgun tight into the shoulder, leaning into the shot and allowing your body to absorb the force, the impact and damage will be greatly lessened.  One of the other problems that arises when hunting birds with a shotgun is that, unlike with most hunting, it requires shooting at a moving target.  This puts a rotational force on the person as they fire which causes additional strain on the body.