In 1945 Roy Weatherby left an insurance job to open a shop in South Gate, California. He brought an unpopular idea: that most wounded and lost animals were not lost through lack of lead, but lack of velocity. The industry of the day argued the opposite, that bullet weight did the work.

Weatherby built cartridges to prove it. The .257, .270, .300, .340 and .460 Weatherby Magnum came from that determination, carrying their bullets faster than was considered reasonable. The problem then was the reverse: no commercial action had enough margin for those pressures.

So he made the rifle. Four prototypes, the first made by Mathewson Tool in 1955, led in 1958 to the Mark V: nine lugs in three rows of three, spreading bolt thrust over far more surface than the usual two lugs and allowing a 54-degree bolt lift. It is not mechanical ornament. It follows from designing the cartridge before the rifle.