Heckler & Koch MP5

The Heckler & Koch MP5 (German: Maschinenpistole 5, lit. 'Submachine gun 5') is a submachine gun developed in the 1960s by German firearms manufacturer Heckler & Koch. It uses a similar modular design to the Heckler & Koch G3, and has over 100 variants and clones, including selective fire, semi-automatic, suppressed, compact, and even marksman variants. The MP5 is one of the most widely used submachine guns in the world, having been adopted by over forty nations and numerous militaries, police forces, intelligence agencies, security organizations, paramilitaries, and non-state actors.
Attempts at replacing the MP5 by Heckler & Koch began in the 1980s, but despite functional prototype weapons having promising performance, a formal successor did not enter commercial production until 1999, when Heckler & Koch developed the UMP. However, despite being more expensive the MP5 remained the more successful of the two designs, because of its preexisting widespread use, design familiarity, and lower recoil due to its roller-delayed action as opposed to the UMP's straight blowback action.
Heckler & Koch, encouraged by the success of the G3 battle rifle in 1959, developed a family of small arms consisting of four types of firearms all based on a common G3 design layout and operating principle. The first type was chambered for 7.62×51mm NATO, the second for 7.62×39mm M43, the third for 5.56×45mm NATO, and the fourth for 9×19mm Parabellum. The MP5 was created for the fourth type as the HK54; under the HK naming system, this categorizes it as a selective fire carbine chambered in a handgun cartridge.
Development began in 1964, and in 1966 the HK54 was adopted by the Bundesgrenzschutz and by Bundeswehr special forces, initially as the MP64, before being redesignated as the MP5. The MP5A1 was introduced in the late 1960s and was the first model to feature the front ring sight and "Slimline" handguard. In 1970, the MP5 and MP5A1 were superseded by the MP5A2 and MP5A3, improvements to the MP5A1 with a fixed stock and retracting stock respectively. In 1974, the MP5SD, an integrally-suppressed variant, was introduced, and in 1976, the MP5K, a redesigned compact variant, was developed per a request for a variant that suited close-quarters combat in South America. In 1977, the original straight magazines were replaced by curved steel magazines. In 1978, the "Tropical" handguard was introduced for the MP5.
In 1980, the MP5 achieved an iconic status during the Iranian Embassy siege, when British Army Special Air Service operatives used MP5s with top-mounted flashlights to assault the embassy and rescue the hostages held inside. Photos of the operation featuring MP5s were widely disseminated in the press and popular media, and drove other military and police units to purchase MP5s as well, quickly making the MP5 widely recognizable and associated with elite counterterrorist units. The MP5 has since become a mainstay in militaries, special forces, and police tactical units across the world, but has gradually been replaced since the late 1990s by rifles, carbines, and personal defense weapons due to changes in armament trends, including growing access to body armor that can stop handgun projectiles.
The MP5 is manufactured under license in several nations including Greece (formerly Hellenic Arms Industry, currently Hellenic Defence Systems), Iran (Defense Industries Organization), Mexico (SEDENA), Pakistan (Pakistan Ordnance Factories), Saudi Arabia, Sudan (Military Industry Corporation), Turkey (MKEK), and the United Kingdom (formerly Royal Ordnance, later moved to Heckler & Koch Great Britain).
The primary version of the MP5 family is the MP5A2, which is a selective fire delayed blowback-operated 9×19mm Parabellum weapon. It fires from a closed bolt (bolt forward) position.
The fixed, free-floating, cold hammer-forged barrel has six right-hand grooves with a 1 in 250 mm (1:10 in) rifling twist rate and is pressed and pinned into the receiver.
The first MP5 models used a double-column straight box magazine, but since 1977, slightly curved steel magazines have been used with a 15-round capacity (weighing 0.12 kg) or a 30-round capacity (0.17 kg empty).
The adjustable iron sights (closed type) consist of a rotating rear diopter drum and a front post installed in a hooded ring. The rear sight is mechanically adjustable for both windage and elevation with the use of a special tool, being adjusted at the factory for firing at 25 metres (27 yd) with standard 8 grams (123 gr) FMJ 9×19mm NATO ammunition. The rear sight drum provides four apertures of varying diameters used to adjust the diopter system, according to the user's preference and tactical situation. Changing between apertures does not change the point of impact down range.
The MP5 has a hammer firing mechanism. The trigger group is housed inside an interchangeable polymer trigger module (with an integrated pistol grip) and equipped with a three-position fire mode selector that serves as the manual safety toggle. Per HK trigger group standards, most MP5 variants have the option of "SEF" or "Navy" trigger groups, with further alterations based on the availability and type of burst fire; the "SE" and "0-1" trigger groups are only available for semi-automatic and civilian variants. While the "SEF" trigger group's fire selector lever is located on the left-hand side of the trigger, the SEF symbols themselves appear on both sides of the trigger grouping; the "Navy" trigger group, among others, are ambidextrous. The safety/selector is rotated into the various firing settings or safety position by depressing the tail end of the lever. Tactile clicks (stops) are present at each position to provide a positive stop and prevent inadvertent rotation. The "safe" setting disables the trigger by blocking the hammer release with a solid section of the safety axle located inside the trigger housing.
The non-reciprocating cocking handle is located above the handguard and protrudes from the cocking handle tube at approximately a 45° angle. This rigid control is attached to a tubular piece within the cocking lever housing called the cocking lever support, which in turn makes contact with the forward extension of the bolt group. It is not however connected to the bolt carrier and therefore cannot be used as a forward assist to fully seat the bolt group. The cocking handle is held in a forward position by a spring detent located in the front end of the cocking lever support which engages in the cocking lever housing. The lever is locked back by pulling it fully to the rear and rotating it slightly clockwise where it can be hooked into an indent in the cocking lever tube.
The bolt rigidly engages the barrel extension—a cylindrical component welded to the receiver into which the barrel is pinned. The delay mechanism is of the same design as that used in the G3 rifle. The two-part bolt consists of a bolt head with rollers and a bolt carrier. The heavier bolt carrier lies up against the bolt head when the weapon is ready to fire and inclined planes on the front locking piece lie between the rollers and force them out into recesses in the barrel extension.
When fired, expanding propellant gases produced from the burning powder in the cartridge exert rearward pressure on the bolt head transferred through the base of the cartridge case as it is propelled out of the chamber. A portion of this force is transmitted through the rollers projecting from the bolt head, which are cammed inward against the inclined flanks of the locking recesses in the barrel extension and to the angled shoulders of the locking piece. The selected angles of the recesses and the incline on the locking piece produce a velocity ratio of about 4:1 between the bolt carrier and the bolt head. This results in a calculated delay, allowing the projectile to exit the barrel and gas pressure to drop to a safe level before the case is extracted from the chamber.
The delay results from the amount of time it takes for enough recoil energy to be transferred through to the bolt carrier in a sufficient quantity for it to be driven to the rear against the force of inertia of the bolt carrier and the forward pressure exerted against the bolt by the recoil spring. As the rollers are forced inward they displace the locking piece and propel the bolt carrier to the rear. The bolt carrier's rearward velocity is four times that of the bolt head since the cartridge remains in the chamber for a short period of time during the initial recoil impulse. After the bolt carrier has travelled rearward 4 mm, the locking piece is withdrawn fully from the bolt head and the rollers are compressed into the bolt head. Only once the locking rollers are fully cammed into the bolt head can the entire bolt group continue its rearward movement in the receiver, breaking the seal in the chamber and continuing the feeding cycle.
Since the 9×19mm Parabellum cartridge is relatively low powered, the bolt does not have an anti-bounce device like the G3, but instead the bolt carrier contains 32.5 g (1.15 oz) of tungsten granules that prevent the bolt group from bouncing back after impacting the barrel extension. The weapon has a fluted chamber that enhances extraction reliability by bleeding gases backwards into the shallow flutes running along the length of the chamber to prevent the cartridge case from expanding and sticking to the chamber walls (since the bolt is opened under relatively high barrel pressure). A spring extractor is installed inside the bolt head and holds the case securely until it strikes the ejector arm and is thrown out of the ejection port to the right of the receiver. The lever-type ejector is located inside the trigger housing (activated by the movement of the recoiling bolt).
Threading is provided at the muzzle to work with certain muzzle devices made by Heckler & Koch, including a slotted flash suppressor, a blank-firing adapter (marked with a red-painted band denoting use with blank ammunition only), a rifle grenade adapter (for use with rifle-style grenades with an inside diameter of 22 mm using a special grenade launching cartridge), and cup-type tear gas rifle grenade adapter. An optional "3-Lug" barrel is also available on some variants for mounting a quick-detachable suppressor.
The MP5SD's 146 mm (5.7 in) barrel has 30 2.5 mm (0.1 in) ports drilled forward of the chamber through which escaping gases are diverted to the surrounding sealed tubular casing that is screwed onto threading on the barrel's external surface just prior to the ported segment. The MP5SD's integral suppressor itself is divided into two stages: the initial segment surrounding the ported barrel serves as an expansion chamber for the propellant gases, reducing gas pressure to slow down the acceleration of the projectile. The second decompression stage occupies the remaining length of the suppressor tube and contains a stamped metal helix separator with several compartments which increase the gas volume and decrease its temperature, deflecting the gases as they exit the muzzle, so muffling the exit report. The bullet leaves the muzzle at subsonic velocity, so it does not generate a sonic shock wave in flight. As a result of reducing the barrel's length and venting propellant gases into the suppressor, the bullet's muzzle velocity was lowered anywhere from 16% to 26% (depending on the ammunition used) while maintaining the weapon's automation and reliability.
The receiver housing has a proprietary claw-rail mounting system that permits the attachment of a standard Heckler & Koch quick-detachable scope mount (also used with the G3, HK33, and G3SG/1). It can be used to mount daytime optical sights (telescopic 4×24), night sights, reflex sights, and laser sights. The mount features two spring-actuated bolts, positioned along the base of the mount, which exert pressure on the receiver to hold the mount in the same position at all times assuring zero retention. All versions of the quick-detachable scope mount provide a sighting tunnel through the mount so that the shooter can continue to use the fixed iron sights with the scope mount attached to the top of the receiver.
A Picatinny rail adapter can be placed on top that locks into the claw rails. This allows the mounting of STANAG scopes and has a lower profile than the claw-rail system.
Standard MP5 variants have the option of two handguards: "Slimline", the original slim checkered metal handguard; and "Tropical", a wider and smoother polymer handguard introduced in 1978.
The MP5SD, MP5K, and SP89 have unique handguards owing to their design differences: the MP5SD handguard is similar to Slimline but larger to fit the integrated suppressor, the MP5K handguard has a built-in foregrip and handstop, and the SP89 handguard is similar to the MP5K's but extended and without the foregrip.
Aftermarket handguards also exist, including newer vented handguards based on the "Tropical" handguard, "dedicated forend" handguards featuring a built-in underbarrel tactical light, and rail integration system-equipped handguards to fit attachments.
The MP5SD ("SD" meaning Schalldämpfer, German for "sound suppressor") is a variant of the MP5 with an integral suppressor, introduced in 1974. The integral suppressor, built around its 5.7-inch barrel, uses a unique two-stage design that allows it to operate silently in most environments, including when wet, while still remaining reliable. The distinctive size of the integral suppressor gives it a unique handguard design, with a modified charging handle to account for it. The MP5SD has a rate of fire of approximately 800 rounds per minute, and is intended for use with both standard and subsonic ammunition.
The MP5K ("K" meaning Kurz, German for "short") is a redesigned compact variant of the MP5, introduced in 1976. Developed from the stockless MP5A1, it features a 4.5-inch barrel incompatible with muzzle attachments, an endcap with sling mount instead of a stock, and a unique handguard with a built-in foregrip. Most components of the MP5K are shortened on account of its compact design, including its bolt, receiver, charging handle, cover, and trigger group frame; the lighter bolt gives it a higher rate of fire, at approximately 900 rounds per minute (as opposed to 800 rounds per minute with the regular MP5). Different variants of the MP5K use either unique open iron sights or redesigned fixed iron sights.
Though the MP5 is normally chambered in 9×19mm Parabellum, two variants and an unreleased kit existed that used different ammunition.
Five prototype firearms based on the MP5 were developed by Heckler & Koch in the 1980s and 1990s, mostly intended as improved variants or potential successors, but were not developed any further.
In the United States, PTR Industries, Zenith Firearms, Dakota Tactical, and Century International Arms manufacture semi-automatic clones of the MP5 that are legally classified as pistols. In 2007, Professional Arms demonstrated the MK5, an MP5 clone that could be rechambered between 9×19mm, .45 ACP, and .40 S&W.