With an impressive 40-round magazine capacity, light recoil, and great penetration at close distances, the CMMG FourSix is here to reimagine the Personal Defense Weapon. Not only is the FourSix the first AR chambered in 4.6x30mm, but it is also the first 4.6x30mm firearm ever released to the U.S. civilian market! What is 4.6x30mm? First introduced in 1999, the 4.6x30mm is known for its pairing with the Heckler & Koch MP7. By design, the 4.6x30mm is a relatively small and lightweight cartridge with minimal felt recoil meant to compete with the 5.7x28mm. Ballistically the 4.6x30mm round is very similar to the 5.7x28mm round in the sense that it is a high velocity, flat-shooting projectile that has great penetration, but where the 4.6x30mm will hold an advantage is in your pocketbook.