6 mm/223

The 6x45 cartridge is the .223 or 5.56 x 45 mm NATO round necked up to 6 mm. It is a fine small game or varmit round. It can be used in small bolt action or Ar-15 type rifles. It was also tested by the US army for a S.A.W. All this information is in #7 cartridges of the world By Frank Barnes. Also in the Sierra reloading manual.

The 6x45 has a rather small powder capacity and will thus give best results using bullets of low to moderate weight (up to approx. 90 grains). Initial velocities are normally between 750m/s and 850 m/s depending on bullet weight. Due to the low velocity and moderate effect on the game, it is a rather popular wildcat cartridge for small game hunting for meat.