The .50 Beowulf (12.7x42mmRB) is a
12mm caliber rifle cartridge
A rifle cartridge is a firearm cartridge (firearms), cartridge primarily designed and intended for use in a rifle/carbine, or machine gun.
Types Full-powered
A full-powered cartridge is a rifle cartridge used interchangeably between servic ...
developed by Bill Alexander of Alexander Arms for use in an
AR-15 rifle.
Design and specifications
The cartridge utilizes a
rebated rim, sized to match the rim of the
6.5mm Grendel round. The case body is very similar in dimensions to the
.500 S&W Magnum revolver
A revolver is a repeating handgun with at least one barrel and a revolving cylinder containing multiple chambers (each holding a single cartridge) for firing. Because most revolver models hold six cartridges before needing to be reloaded, ...
cartridge, being slightly longer and fully tapered for automatic feeding in the weapon.
The round is intended to improve
stopping power
Stopping power is the supposed ability of a weapon – typically a ranged weapon such as a firearm – to cause a target (human or animal) to be incapacitated or immobilized. Stopping power contrasts with lethality in that it pertains only to a ...
greatly at short- to medium-range as compared to the standard
5.56×45mm NATO round. One of its advertised uses is at vehicle checkpoints, since the heavy bullet's flight path is not easily deflected by auto glass or standard vehicle body panels.
Design limitations
With normal bullet weights between , overall
cartridge length shorter than that of an
AR-15 magazine well, and holding to pressures of 33,000 psi limited by the AR bolt strength system,
the .50 Beowulf is best described as a low-velocity, heavy caliber, making its ballistics roughly equivalent to those of early
.45-70 Government rounds rather than the higher pressure rounds tolerated by
lever-action rifles such as the
Marlin Model 1895.
Proprietary status
The .50 Beowulf is a