The KS-23 is a Russian shotgun which is fitted with rejected barrels for 23mm cannons. The barrels, while not suitable for use with the higher pressures of the cannon round, are perfectly safe for use as a shotgun barrel. At approximately 6 gauge in terms of bore size, the KS-23 fires a round much larger than the vast majority of shotguns produced in the United States. It is currently in service with the Russian military and police agencies with a version available for civillians; however, the weapon is currently prohibited from import into the United States.
Thanks to you, I googled KS-23 and I found out that it was created for riot police and prison guards. It fired rubber bullets and tear gas shells like any other shotgun, but it also came with a muzzle adapter to facilitate firing tear/CS gas mortars from it's muzzle using a blank cartridge. After reading about the specifications, I was thinking that if people wanted something similar in the U.S, they could buy any one of the pump action slug guns from any number of manufacturers. The slug guns come with-though a smaller diameter-a rifled barrel and are fed by an under barrel tube magazine like the Russian shotgun.
Thanks to you, I googled KS-23 and I found out that it was created for riot police and prison guards