The .350 Legend, also called 350 LGND (9×43mmRB), is a SAAMI-standardized straight-walled intermediate rifle cartridge developed by Winchester Repeating Arms. The cartridge was designed for use in American states that have specific regulations for deer hunting with straight-walled centerfire cartridges. At the cartridge's introduction, Winchester claimed that the .350 Legend was the fastest production straight-walled hunting cartridge in the world, although some .450 Bushmaster .444 Marlin and .458 Winchester Magnum loads are faster and have much more energy, and the .350 Legend would be surpassed in 2023 by the .360 Buckhammer. It is designed for deer hunting out to a maximum effective range of 250 yards (230 m).

The Winchester Repeating Arms Company was a prominent American manufacturer of repeating firearms and ammunition. The firm was established in 1866 by Oliver Winchester and was located in New Haven, Connecticut. The firm went into receivership in 1931 and was bought by the Western Cartridge Company, a forerunner of the Olin Corporation. The Winchester brand name is still owned by the Olin Corporation, which makes ammunition under that name. The Winchester name is also used under license for firearms produced by two subsidiaries of the Herstal Group – FN Herstal of Belgium and the Browning Arms Company of Ogden, Utah.