There are a couple of semi auto shotguns that will cycle without blank adaptors but the FFXhot loads must be used. They function at about 90% which is not reliable enough to take chance with during filming. This is mainly due to the inconsistant nature of shotgun blanks. Add a slight restriction and the consistancy of the burn and pressure increases.
The Milkor M32 40mm although not a true gas operated semi auto will work on a 12ga or .45-70FF load. These loads develop a pulse that will depress the spring loaded cylinder pin which lets the pre wound cylinder advance to the next position. It fires as fast as you can pull the trigger.

4570guy