eat dick
It is called the Mossberg 45 Pistol.
6mm of either .12 or .20 gram bbs. 6mm of either .12 or .20 gram bbs.
It depends we're it's not functioning correctly, you best bring your gun back to the retailer and see what they can do
It depends on the specific gun and where you are hit. At a minimum, a cotton T-shirt getting hit by a 180 Feet Per Second (FPS) projectile stings like hell. As the speed of the projectile increases, it begins to kill worse and worse. 260 FPS will split the skin just from the hydraulic shock of the impact. And that hurts like all hell. Heavy clothing, such as loose fitting denim, will generally blunt the force of the impact enough to take away most pain. Just remember, Momentum = (mass) x (velocity squared), so as speed goes up, pain goes up a lot faster. Basically, in short, if you shoot someone in the butt who is not wearing jeans with an airsoft gun that shoots faster than 200 FPS, they will probably kick the snot out of you.
There are 3 standard shotguns in current use- the M500, M590 and M590A1. Three other shotguns are in limited issue- the M870, the M1014 and the M26. As far as why, the answer would be the same as for any military weapon- the military found a need, issued specifications, manufacturers submitted samples and were selected to produce that weapon.