Roy Weatherby had expected that the .378 Weatherby Magnum to make some headway in the African continent but believed that his cartridge was being bypassed for low velocity, big bore cartridges by professional hunters who he felt were resistant to change. Furthermore, new regulations prohibiting the hunting of heavy, thick skinned, dangerous game with sub-.40 caliber (10.16 mm) cartridges were being enacted in some African countries. These regulations would essentially ban the use of all previous Weatherby cartridges for the hunting of elephant, African Cape buffalo and rhinoceros.[5]
In response to these factors, Roy Weatherby believed that it was necessary to provide hunters a Weatherby cartridge that could be used to hunt African dangerous game in the countries which had legislated against hunting with sub-.40 caliber rifles. He accomplished this by necking up the .378 Weatherby Magnum case to accept a .458 caliber bullet. He named the new cartridge the .460 Weatherby Magnum. The first rifles for the .460 Weatherby Magnum were built on Brevex Magnum Mauser action.[5]
However, Roy Weatherby was not the first cartridge designer to neck up the .378 Weatherby Magnum to .45 caliber (11.6 mm). That distinction belongs to John Buhmiller, a gunsmith and hunter from Montana. Buhmiller named his cartridge the .45 Weatherby. He had success with the cartridge in Africa shooting Cape buffalo and rogue elephants in 1956, a year before Roy Weatherby began work on his own .45-caliber cartridge
The .460 Weatherby Magnum was the world's most powerful commercially available sporting cartridge for 29 years until the advent of the .700 Nitro Express by Holland & Holland, London, England, in 1988 developing approximately an average energy of 8,900 foot-pounds (12,100 J) of muzzle energy with a 1,000 gr (65 g) bullet at 2,000 ft/s (610 m/s). However handloaders can push the cartridge to generate as much as 15,000 foot-pounds (20,000 J) of energy in a modern bolt action, by using a 1,000 gr (65 g) bullet fired at 2,600 ft/s (792 m/s). However, doing so necessitates a rifle so heavy it is almost inoperable for hunting purposes. The .700 Nitro Express was itself eclipsed in only five years by the 1993 introduction by A-Square of the .577 Tyrannosaur. The .577 T-Rex develops approximately 10,180 foot-pounds force (13,800 J) with a velocity of 2,460 ft/s (750 m/s).
The .460 will launch a 500-grain (32 g) bullet at a chronographed velocity of 2,700 ft/s (820 m/s) from a 26-inch (660 mm) barrel, measuring 8,100 ftâ‹…lbf (11,000 J) of muzzle energy.[3] Prior to the arrival of the .460 Weatherby Magnum on the hunting scene, the .600 Nitro Express had been considered to be the most powerful cartridge in terms of energy.[4]
https://en.wikipedia.org/wiki/.460_Weatherby_Magnum
