Magnum Research BFR

The Magnum Research BFR is a single-action revolver manufactured by Magnum Research. Modelled after the Colt Single Action Army, it is made from stainless steel and chambered for a number of very powerful pistol calibres, such as .500 S&W Magnum, as well as several calibres traditionally used in rifles, such as .30-30, .450 Marlin and .45-70 Government. The name "BFR" officially is an acronym for "Big Frame Revolver", although other meanings, such as "Big Finest Revolver", or "Biggest, Finest Revolver," and even in some cases, "Big Fucking Revolver" have also been used.
Available cartridges.
The BFR comes in two basic models, one with a long cylinder for larger rifle cartridges, and one with a more traditional revolver cylinder length (called "short" by Magnum Research). Some models that use identical bores such as the .45/70 and .450 Marlin can be made with two cylinders for the same gun.
Magnum Research makes these guns in custom calibers and discourages the use of most rimless cartridges in their revolvers due to mechanical issues. The BFR can be customized for the .50 Beowulf cartridge. These revolvers were originally made by DMAX in Springfield, South Dakota, until Magnum Research bought them out.