A laser sight will do more to improve your odds of hitting the target than using birdshot or small buckshot ever will.
Magpul did a video on shotguns once and showed how even at close ranges there was no useful difference between buckshot and birdshot at close ranges. Might as well hit the guy with everything you can rather than pepper him with bb's he can pick out later.
Laser sight will make you hit the target every time. They are a good investment.
