For tactical use, a semi-automatic shotgun is a superior platform to a pump action, and the new Savage Renegauge is excellent evidence for that statement.
Probably the most radical shotgun on the market, the IWI US Tavor TS12 is a semi-automatic bullpup shotgun that feeds from a three-tubed rotating reservoir.
The EAA MC312 Tactical is an inertial-action, semi-automatic shotgun owning a 18.5-inch barrel, a fiber-optic front sight and an included red-dot optic.