Shotgun scabbards are pretty popular because of their tactical look and special features. They are mostly used by breachers or regular shooters which use scabbards to carry a shotgun. They are also popular among preppers and survivalists.
Beez Combat Systems for Remington 870 (Shotgun Scabbard and Chest Rig)
Recently, I have found out about Beez Combat Systems. This is company which produces lots of products for military and law enforcement.
I think that two of their tactical products will be the most interesting for readers of the Rem870.com blog: BCS Tactical Shotgun Scabbard and BCS Tactical Shotgun Shell Chest Rig.