Heckler & Koch UCP

The Heckler & Koch Universal Combat Pistol (HK UCP), a double action, semi-automatic handgun also known as the HK P46, was developed under commission for the German Bundeswehr.

The concept for the UCP was later discontinued at the prototype stage.

History and Description
The UCP was to be the companion side arm to the HK MP7 submachine gun, using the same HK 4.6×30mm bottlenecked cartridge (see internal ballistics). The 4.6×30mm round is a direct competitor to the 5.7×28mm by Fabrique Nationale de Herstal (FN). As such, the UCP is a direct competitor to the FN Five-seven pistol. Both have greater armor-piercing capabilities and less recoil compared to other commonly used military handgun cartridges, such as the 9×19mm Parabellum or .45 ACP.

The UCP operates on the delayed-blowback operating principle. The external design of the UCP appears to be borrowed from the HK P2000 pistol, and includes ambidextrous controls, interchangeable backstraps, and a MIL-STD-1913 Picatinny-type rail system for the attachment of accessories. Like the USP and P2000 series of pistols, the trigger mechanism is reported to be modular and capable of different configurations. The UCP is designed to accept an extended, threaded barrel capable of accepting the attachment of a sound suppressor made by Brügger & Thomet. Initial speculation that the UCP will accept 40-round MP7 magazines appears to be false.

The design remained in the prototype phase, and had been reported as entering limited trials with the Bundeswehr.

In July 2009, HK USA's president, Wayne Webber, indicated that the UCP project has been cancelled because "HK felt it did not provide adequate ballistics in handgun form."