The .50 Peacekeeper is a wildcat

Wildcat cartridge

A wildcat cartridge, or wildcat, is a custom cartridge for which ammunition and firearms are not mass produced. These cartridges are often created in order to optimize a certain performance characteristic of an existing commercial cartridge.Developing and using wildcat cartridges does not...

 rifle

Rifle

A rifle is a firearm designed to be fired from the shoulder, with a barrel that has a helical groove or pattern of grooves cut into the barrel walls. The raised areas of the rifling are called "lands," which make contact with the projectile , imparting spin around an axis corresponding to the...

 cartridge

Cartridge (firearms)

A cartridge, also called a round, packages the bullet, gunpowder and primer into a single metallic case precisely made to fit the firing chamber of a firearm. The primer is a small charge of impact-sensitive chemical that may be located at the center of the case head or at its rim . Electrically...

 that was designed by J.D. Jones of SSK Industries. The .50 Peacekeeper uses a .460 Weatherby Magnum

.460 Weatherby Magnum

The .460 Weatherby Magnum is a belted, bottlenecked rifle cartridge, developed by Roy Weatherby in 1957. The cartridge is based on the .378 Weatherby Magnum necked up to accept the bullet. The original .378 Weatherby Magnum parent case was inspired by the .416 Rigby...

 case that has been re-sized to accept a 50 caliber (.510 inch diameter) bullet.

The .50 Peacekeeper is usually loaded with bullets that weigh in the range of 650 to 750 grains (gr), and with muzzle velocities that range from 2200 to 2400 ft/s (670.6 to 731.5 m/s). A 750-gr bullet fired at 2205 ft/s (672.1 m/s) carries roughly 8100 ft.lbf of energy. Recoil

Recoil

Recoil is the backward momentum of a gun when it is discharged. In technical terms, the recoil caused by the gun exactly balances the forward momentum of the projectile and exhaust gasses, according to Newton's third law...

 in a 12-15 pound rifle is slightly less than that of a 30 pound rifle chambered in .50 BMG

.50 BMG

The .50 Browning Machine Gun or 12.7×99mm NATO is a cartridge developed for the Browning .50 caliber machine gun in the late 1910s. Entering service officially in 1921, the round is based on a greatly scaled-up .30-06 cartridge...

.