Introduced in 1955 the 243 was intended to serve as a true dual-purpose varmint/deer cartridge based on the 308 Winchester case. The cartridge has proved to be an excellent performer.The 243 is a tremendously versatile cartridge well suited to game from varmints to mule deer. Loaded with Sierra?s 90-grain GameChanger hunters can also expect strong performance at the end of the line.