The Magnum Research Big Frame Revolver (abbreviated BFR as well as being named "Biggest, Finest Revolver" among other interpretations of BFR) is a series of single action revolvers produced by Magnum Research.
The BFR was initially designed around the purpose of firing larger calibre sizes, calibres which would be more familiar to rifle users than handgun shooters. To fulfill this purpose the BFR is manufactured with a relatively long cylinder to accomodate the longer cartridges of rifle rounds. This cylinder is made of stainless steel and varies in length according to the cartridge length (ie rifle or short (handgun) length cartridges).
Barrel lengths also vary according to calibre, with shorter barrel lengths only available on BFR's chambered to fire shorter cartridges. Although custom barrels can be ordered from Magnum Research, standard sizes include 6.5in (short length cartridges only), 7.5in and 10in. All of these barrels are rifled to the optimum twist rate for the cartridge the customer ordered. As of 2013 5in length barrels have been introduced.
The BFR boasts several safety features seen on various other revolver designs. Chief among these is the Ruger-based transfer bar mechanism, which prevents the gun firing unless the trigger is pulled. Weaver style mounts are fitted to the BFR as standard to the barrel to allow the fitting of scopes. Other rails can be ordered from Magnum Research as custom fittings.
The BFR is available in a range of calibre sizes. These are divided into two groups: Long Cylinder (rifle rounds) and Short Cylinder (pistol rounds) with all various calibres shot from a five shot cylinder.
Short Cylinder calibres range from the .218 Bee to the .50 Action Express, with BFR's which chambered for the .50 Action Express occasionally modified to fire the .50 Beowulf cartridge. Long Cylinder BFR's are capable of firing virtually all cartridges larger than the .30-30 Winchester including the .460 S&W Magnum and .500 S&W Magnum "super" cartridges.
The BFR is sold by Magnum Research primarily as a target/relaxed shooting revolver, focusing on allowing the user to fire much more powerful cartridges than other handguns are capable of. As virtually the same frame is used for every calibre size (only minor modifications are made to better balance the BFR) very little recoil is produced when smaller calibre BFRs are fired.
The BFR is also among an exclusive club of firearms that are capable of firing Smith & Wesson's largest and most powerful cartridges, a feat that only Smith & Wesson's own handguns are capable of achieving (ie the Smith & Wesson Model 460 or Model 500). Perhaps the most intriguing fact about the BFR is the fact that some examples of the BFR are chambered to accept the 140 year old .45-70 Government cartridge, which was originally used with the Springfield Model 1873 rifled musket (both) originally designed in 1873.