Nice Winchester 1200 12 Gauge. Davis M500 Speed Feed synthetic stock with ammo storage. Shoots 2 3/4 and 3 inch shells. Cylinder Bore - The cylinder bore of a shotgun is the diameter of the opening at the end of the barrel. Because they lack a choke, they are intended for home or self-defense. It distributes about 40% of a shell's total pellets in a 30 inch circle at 40 yards. It is most often used by law enforcement for service shotguns.