.350 Legend Ammo (9×43 mm), also called 350 LGND, is a SAAMI-standardized straight-walled hunting 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.Winchester claims that the .350 Legend is the fastest production straight-walled hunting cartridge in the world, although some .444 Marlin and .458 Winchester Magnum loads are faster. It is designed for deer hunting out to a maximum effective range of 250 yards (230 m).Ohio’s Deer Hunting Regulations allow the use of a straight-walled rifle cartridge with a minimum caliber of .357 inches (9.1 mm). Consequently, the .350 Legend is a legal hunting rifle cartridge there.
The .350 Legend Ammo shares many characteristics with the .223 Remington, the overall cartridge length is 2.26 inches (57 mm) long with a rim diameter of .378 inches (9.6 mm), but it is not derived from the .223 Remington.Because of its similarities to the .223 Remington and 5.56 mm NATO, the .350 Legend is suitable for use in AR-15 type semiautomatic rifles,and will fit in most standard AR-15 magazines without modification.