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In addition to the commonly encountered shotgun actions already listed, there are also shotguns based on the Martini-Henry rifle design, originally designed by British arms maker W.W. Greener.

Some of the more interesting advances in shotgun technology include the versatile NeoStead 2000 and fully automatics such as the Pancor Jackhammer or Auto-Assault 12.

In 1925, Rodolfo Cosmi produced the first working prototype hybrid semi-automatic shotgun, which had an 8-round magazine located in the stock. While it reloaded automatically after each shot like a semi-automatic, it had a break-action to load the first shell. This design has only been repeated once, by Beretta with their UGB25 automatic shotgun. The user loads the first shell by breaking the gun in the manner of a break-action shotgun, then closes it and inserts the second shell into a clip on the gun's right side. The spent hulls are ejected downwards. The guns combine the advantages of the break action (they can be proven to be safe by breaking open, there are no flying hulls) with those of the semi-automatic (low recoil, low barrel axis position hence low muzzle flip).

The Italian firearms manufacturer Benelli Armi SpA also makes the Benelli M3, a dual-mode hybrid shotgun that allows the user the choice of semi-automatic or pump-action operation. Pump-action operation is employed when shooting less energetic shells (such as baton rounds) that do not generate enough recoil to operate the semi-automatic mechanism. Conversely, the semi-automatic mode can be employed with more powerful shells, absorbing some of the recoil. Switching between the two modes is done by manipulating the ring located at the front of the foregrip.

The French firearm manufacturer Verney-Carron produces the Véloce shotgun, a "lever-release blowback firearm" using bolt catch mechanism like its similarly designed SpeedLine rifle. The Véloce is in essence a modified inertia-driven semi-automatic shotgun, but after blowback the bolt is trapped by a bolt stop and cannot return to battery unless it is manually released by depressing a thumb lever near the tang of the grip. Because the gun will not chamber a new round without manual actuation, the design is technically not really a self-loading, and Verney-Carron described it as a "manual repeating shotgun". When Australian firearm dealers tried to import the Véloce shotgun in 2018, Greens ' David Shoebridge and anti-gun groups such as Gun Control Australia caused a moral panic on the mainstream media, calling it "semi-semi-automatic" that needed to be prohibited as a "rapid-fire weapon".