The 4.6mm cartridge was developed by HK for the MP7 and its companion sidearm, the UCP pistol. The UCP never got past the prototype stage, but the 4.6x30mm has definitely made its mark in the MP7.

The MP7 personal defense weapon (PDW) seems to embody the small and fast paradigm. Devised by Heckler & Koch Inc., (www.hecklerkoch-usa.com), it fires a 4.6 30-mm round (equivalent to .18 caliber ...

Looking almost like an oversized pistol, the Heckler & Koch MP7 is a cross between a submachine gun and a carbine that serves around the world in the hands of law enforcement and special operations ...