The UCP (Universal Combat Pistol), also known as the HK P46, is a semi-automatic pistol manufactured by Heckler and Koch that chambers the 4.6x30mm round. The weapon made as a companion sidearm to the MP7, since both weapons chamber the same round. The weapon never got out of its prototype stage, and was cancelled before production had begun.
Tom Clancy's Rainbow Six: Vegas 1 and 2Edit
The weapon was supposed to appear in both Tom Clancy's Rainbow Six: Vegas and Tom Clancy's Rainbow Six: Vegas 2, but was later cut from the final product. This weapon appeared in the files of the PC versions of both games.