Shotgun Best Short Range Weapon

"The multiple projectile ability of a shotgun greatly increases the probability of a hit on an assailant, and the multiple projectiles increase the likelihood of a disabling hit. A typical police load would be a 12-gauge 2 3/4-inch (70 mm) 00 ("double-aught") buckshot shell consists of 9 .33 caliber (8.5 mm) round balls, each of which is similar in size and velocity to a lightweight handgun bullet. This shot spreads out to a greater or lesser degree depending on the barrel choke, and can be effective at ranges as far as 75 yards (70 m). The delivery of the large number of projectiles simultaneously makes the shotgun the most effective short range weapon commonly used, with a hit probability 45% greater than a submachine gun, and twice as great as an assault rifle."

Wikipedia entry under "Riot Shotguns"