The Heckler & Koch MP7 (Maschinenpistole 7) is a German Personal Defence Weapon (PDW) designed and manufactured by Heckler & Koch (H&K) and chambered for the HK 4.6×30mm cartridge. It was designed with the new cartridge to meet NATO requirements published in 1989, as these requirements call for a personal defense weapon (PDW) class firearm, with a greater ability to penetrate body armor than current weapons limited to conventional pistol cartridges. The MP7 went into production in 2001. It is a direct rival to the FN P90 , also developed in response to NATO's requirement. The weapon has been revised since its introduction and the latest production variants are the MP7A1 and MP7A2 .   
The proliferation of high-quality body armor has begun to make guns that fire pistol ammunition (such as Heckler & Koch's earlier MP5 submachine gun or USP pistol) ineffective. In response to this trend, Heckler & Koch designed the MP7 (along with the now cancelled UCP pistol, which uses the same ammunition) to penetrate body armor while being small enough to be used in place of either a pistol or a submachine gun.   
The MP7 uses a short-stroke piston gas system as used on H&K's G36 and HK416 assault rifles, in place of a blowback system traditionally seen on sub-machine guns including those by H&K.  The 4.6×30mm ammunition is exclusive to the gun and offers low recoil .   This ammunition is unique among submachine guns in that the bullet is made almost entirely of a hardened steel penetrator instead of softer copper or lead.
The MP7 allows a conventional 20-round, 30-round or 40-round box magazine to be fitted within the pistol grip (the 20-round magazine being comparable in size to a 15-round 9×19mm magazine, while the 40-round magazine compares to a 30-round 9×19mm magazine). It features an ambidextrous fire selector, bolt catch lever and magazine release. It has an extendable stock and a folding front grip; it can be fired either one-handed or two-handed.   It is compact and light, due to the use of polymers in its construction.
The MP7 has a cyclic rate of fire of 950 rounds per minute (RPM).
The MP7's specially designed armour piercing (AP) high velocity rounds consist of either copper plated solid steel (DM11), alloy plated steel jacket (DM21) or copper-alloy-jacketed lead core projectiles (Fiocchi FMJ ZP). Standard AP high velocity DM11 (Ultimate Combat) round with a 2.0 g (31 gr ) projectile has a muzzle velocity of 720 m/s (2,362 ft/s) and has a muzzle energy of 506 J (373 ft-lbf).  The DM11 round penetrates the NATO CRISAT target (20 layers of kevlar with 1.6 mm titanium backing) even at 200 m .  The round has a small diameter, allowing for redoubling penetration capability and high capacity in a very small magazine. 
VBR of Belgium produces a 4.6×30mm 2-part controlled fragmenting projectile that is claimed to increase the content of the permanent wound cavity and double the chance to hit a vital organ.    Heckler & Koch claims that the CPS Black Tip ammunition made by Fiocchi has a muzzle energy of approximately 525 J, which would be comparable to 9×19mm Parabellum rounds.  
The MP7 features a full-length, top-mounted Picatinny rail that comes as standard with folding fore and rear iron sights attached. When the sights are folded flat, they resemble Patridge style open sights . Folded up, they feature aperture sights . The sights can easily be removed by loosening a single screw and lifting them off. It can fit additional rails on the sides of the barrel, which allow it to mount commercial optical sights ( telescopic and red dot sights), laser aiming modules (LAM), and tactical flashlights . It can also accept a suppressor , and its tailor-made suppressor does not interfere with its accuracy or rate of fire.
- PDW : The first prototype was shown in 1999 and was designated as the 'PDW' (Personal Defense Weapon). It had a short Picatinny rail on the top and a smooth pistol grip surface.
- MP7 : In 2001 it was designated as the 'MP7' and went into production. Changes includes a full length Picatinny rail, a thick curved stock and an anti-slide surface on the pistol grip much like the HK USP . It also features a folding iron sights mounted on the Picatinny rail and the button to fold the foregrip was made larger for easier operation.
- MP7A1 : In 2003 its designation was changed to 'MP7A1' and featured a redesigned pistol grip with a different surface and curved shape, a smaller stock with a straight buttpad, side mounted picatinny rails as standard and the folding iron sights were made more compact. The weapon was made slightly longer, but because the stock was shortened, the overall length did not change. The stock is also able to be locked into 3 positions. Recent MP7A1 models have a trigger safety similar to a Glock pistol ; the middle section of the trigger must be pulled first before the outer part will move. This helps to stop accidental discharges if the trigger is bumped.  
- MP7A2 : A variant without the folding front grip but features a Picatinny rail to mount various grips in line with the user's preference.
- MP7-SF : A semi-automatic only variant of the MP7 which is currently used by the Ministry of Defence Police in United Kingdom.
  Italy 9th Parachute Assault Regiment −−−  N.O.C.S. of Polizia di Stato−−−  Japan Japanese Special Forces Group −−−  Jordan Royal Guards, Special forces 71 Antiterrorism Unit−−−  Malaysia Pasukan Khas Laut (PASKAL) counter-terrorism group of the Royal Malaysian Navy MP7A1−2006   Pasukan Gerakan Khas (PGK) counter-terrorism divisions of the Royal Malaysia Police −2007   Mauritius GIPM−2013- Norway Norwegian Armed Forces 6,5002007    Oman −−−−  Republic of Korea Republic of Korea National Police Agency SWAT−−−   Presidential Security Service −−−  Romania SRI Brigada Antitero MP7A1−−  Serbia Serbian Special ForcesMP7A1--  Russia Spetsnaz special forces unit of the Russian Army MP7A1--  United Kingdom Ministry of Defence Police and Metropolitan Police MP7-SF−−    United States United States Naval Special Warfare Development Group −−−   Sunnyvale Department of Public Safety in California MP7A1−−    Vatican City Pontifical Swiss Guard −− 
Heckler & Koch UCP
The Heckler & Koch Universal Combat Pistol (HK UCP) , also known as the HK P46 designed by Heckler & Koch , is a double action , semi-automatic handgun 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 would have been 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 operated on the delayed-blowback operating principle. The external design of the UCP appears to have been 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 have been modular and capable of different configurations. The UCP was designed to accept an extended, threaded barrel capable of accepting the attachment of a sound suppressor made by Brügger & Thomet .
The design remained in the prototype phase as of 2006, and had been reported as entering limited trials with the Bundeswehr.
In July 2009, HK USA's president, Wayne Weber, indicated that the UCP project has been cancelled because "HK felt it did not provide adequate ballistics in handgun form."