I use a 2 3/4" 00 magnum shell containing 12 pellets and 4 drams of powder. I also have some reg. 2 3/4" 00 shells containing 9 pellets and has 2 3/4 drams of powder. And all shot sizes are standard and uniform no matter what company manufactures them. http://www.remington.com/ammo/shotshell/exp_bucksh.htm or http://www.remington.com/ammo/ballis...l/slubkbal.htm