The only bolt action smooth bore 12's I know of are the older ones like the Geha Mauser conversion (integral mag), the Mossberg Model 195 (2+1) that takes mags, the Kessler Model 128FR (2+1) that takes mags, the Spiegel MODEL 32-0 ((2+1) that takes mags and then there were the JC Higgins, Sears, etc. version that were usually re-badged versions of the aforementioned guns.
In general, there is a reason these guns ceased production in favour of pumps. They simply were not good performers compared to the other action types out there. I had a Mossberg many years ago as my loaner and the detachable mag was the bane of its existence. It did not feed all that well with most brands of ammo and the mag was prone to dropping free. The release was not very stiff and caught on tree branches easily when going too/from duck blinds. After 2 mags lost in the swamps, and the hunt for a replacement, it got moved along in favour of other guns.
In modern guns, it looks like you basically have the Savage 212/220 series. I've never seen a mag for these that holds more than 2, but one may exist? I would not call these tactical. All models currently sold (maybe all EVER sold?) are rifled and are predominantly in 20 gauge, though the limited number of 212 variants are 12 gauge.
These are meant only for saboted slugs, and are essentially bolt action rifles for areas that only allow shotgun hunting. They are built for one thing only - the fire a saboted slug at rifle velocities and ranges with mounted optics. Perhaps not what you are looking for.
Hope that helps.