For those who like the M16/AR15 platform, Akdal Arms, a Turkish company is offering a gas operated, semi-automatic shotgun built on an AR frame. It is the MKA 1919. Like the AR, it is easy to maintain and the 19.7-inch barrel can be easily removed from the upper receiver. Charge the shotgun with the familiar charging handle on the receiver and fire with the look and feel of an AR series rifle.
The MKA 1919 offers a 12 GA, 5-round magazine with bolt release in same location as the M16/AR15 and a manual safety located on the left side of the receiver above the pistol grip. It has the traditional carry handle and M16-style sights. The upper receiver has a Picatinny rail to attach a tactical sight and other optional equipment.
This shotgun has been in service of the Turkish land forces and is now available in the US through EAA. It is becoming as popular with military and police as the Benelli M3 that can be used as a pump-action or semi-automatic.
You may have to suffer a backorder because this firearm has been popular. The MSRP is $699 for the standard model that includes two 5-round magazines and three internal choke tubes (CYL, MOD, FULL).