The Heckler & Koch MP7 (Maschinenpistole 7) is a personal defence weapon (PDW) chambered for the HK 4.6×30mm armor-piercing cartridge designed by German defense manufacturer Heckler & Koch. It was designed together with the new cartridge to meet NATO requirements published in 1989, as these requirements call for a compact PDW-class firearm, with a greater ability to defeat body armors than the current submachine guns using conventional pistol cartridges.

The MP7 went into production in 2001, and 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.^[8][9][10]

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 and USP pistol) ineffective. In response to this trend, Heckler & Koch designed the MP7 (along with the 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.^[8][9][11]

The MP7 uses a short-stroke piston gas system as used on H&K's G36 and HK416 in place of a blowback system traditionally seen on sub-machine guns including those by H&K.^[12] The 4.6×30mm ammunition is exclusive to the gun and offers low recoil.^[8][9] 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-, 30- or 40-round box magazine to be fitted within the pistol grip (the 20-round magazine is 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 (MP7 and MP7A1 variants, MP7A2 lacks the folding front grip); it can be fired either one-handed or two-handed.^[8][9] 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 armor 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).^[13] The DM11 round penetrates the NATO CRISAT target (20 layers of kevlar with 1.6 mm titanium backing) at 200 m.^[14] The round has a small diameter, allowing for redoubling penetration capability and high capacity in a very small magazine.^[15]

VBR of Belgium produces a 4.6×30mm two-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.^[8][9][16] 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.^[17][18]

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.