 The .333 Jeffery and the .333 Jeffery Flanged are both bottlenecked centerfire rifle cartridges.Originally both cartridges were released with two factory loads, one with a bullet of and the other with a bullet of .The .333 Jeffery, also known as the .333 Jeffery Rimless Nitro Express or as the .333 Rimless Nitro Express, is a rimless cartridge intended for use in magazine rifles.