The .500 Bushwhacker is a .50 caliber semi-rimmed revolver cartridge developed by TII Armory for the Magnum Research BFR revolvers. It is currently the most powerful revolver cartridge in the world, offering a similar level of ballistic performance to African stopping rifles, such as the .416 Rigby and .470 Nitro Express. Given comparable barrel lengths, it is nearly twice as powerful as the .500 S&W Magnum. A 10-inch barrel revolver chambered in the cartridge is capable of penetrating 96-inches of 10% Clear Ballistics gel.

The Magnum Research BFR is a single-action revolver manufactured by Magnum Research. Modeled after the Ruger Blackhawk, it is constructed of stainless steel and chambered for a number of powerful handgun cartridges, such as .460 S&W Magnum and .500 S&W Magnum; popular rifle chamberings, including .30–30 WCF, .444 Marlin, and .45-70 Government; and even .410 bore shotshells. Notably, the BFR platform has also served as the basis for custom caliber conversions to 19th century big game cartridges such as the .50–110 WCF and .50-90 Sharps, as well as the .500 Bushwhacker, which is currently considered to be the most powerful handgun cartridge in the world in terms of muzzle energy. The name "BFR" originally stood for "Brainerd’s First Revolver", in reference to Brainerd, Minnesota, where the early BFRs were manufactured. Officially the acronym now stands for "Biggest, Finest Revolver", though it was rebranded for a time as the "Big Frame Revolver" after Magnum Research's 2010 acquisition by Kahr Arms. It is sometimes referred to as the "Big Fucking Revolver", but this is a misnomer often used for humorous effect and has never been officially sanctioned by manufacturers.