I have found these websites useful.
http://www.firearmstactical.com/
http://ammo.ar15.com/project/Self_Defense_Ammo_FAQ/index.htm#SHOTGUN AMMUNITION
Here is a useful website. It has a insurance policy to help cover lawyer fees while the investigation is on going if you have used your gun in a self defense manner. Lawyer fees can add up in no time. It's called The Self-defense Shield.
https://www.usconcealedcarry.com/