While one might not expect to find a threaded muzzle, Picatinny rail and fiber-optic sights on an Old West-style, single-action revolver, that's exactly what Heritage Manufacturing did with its new Rough Rider TC (Tactical Cowboy).
With the increasing popularity of the AR-15-style rifle, Picatinny rails and chassis systems for bolt-action rifles, being able to quickly attach a bipod is a must.
Looking to add a red dot to your full-size semi-automatic, but don't want to commit to gunsmithing? The UM Tactical UM3 Sight Mount may be the solution.