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The Heckler & Koch MP5 (German: Maschinenpistole 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,[14] including selective fire, semi-automatic, suppressed, compact, and even marksman variants.[15] 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.[16]
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.[17] Despite being more expensive however, the MP5 remained the more successful of the two options, owing to its preexisting widespread use, design familiarity, and lower recoil due to its roller-delayed action as opposed to the UMP's straight blowback action.[18]
History
Heckler & Koch, encouraged by the success of the G3 battle rifle, 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 the 7.62×39mm M43, the third for 5.56×45mm NATO, and the fourth for the 9×19mm Parabellum. The MP5 was created for the fourth type, and was initially known as the HK54; under the HK naming system, this categorizes it as a selective fire carbine chambered in a handgun cartridge.[19]
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.[19] 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 In 1970, the MP5 and MP5A1 were superseded by the MP5A2 and MP5A3, improvements to the MP5A1 with a fixed stock and retracting stock respectively.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.[20] 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 cartridges.[21]
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).[22]
Design
The primary version of the MP5 family is the MP5A2, which is a lightweight, air-cooled, selective fire delayed blowback operated 9×19mm Parabellum weapon with a roller-delayed bolt. It fires from a closed bolt (bolt forward) position.[23]
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.[24]
Features
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).[24]
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.[25] 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.[24]
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.[24]
Operating mechanism
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.[26]
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.[26]
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.[26]
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).[26]
Accessories
Barrel accessories
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.
MP5SD 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.[24]
Receiver
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.
Handguard
Standard MP5 variants have the option of two handguard variants: "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.[27]
Variants
MP5
- HK54
- Original pre-designation model, introduced in 1964. It has a charcoal-gray phosphated finish rather than the matte-black lacquered finish used on later models. The handguard resembles the "Slimline" handguard but is narrower and has slots along it. Its bolt carrier is longer and heavier than that of the final MP5, and it uses a flip-up "ladder" rear sight similar to that used on early G3 models. It uses straight steel magazines with plastic followers and distinctive "waffle" rib imprints for reinforcement.[28]
- MP5
- The basic MP5, based on a modified and improved HK54, introduced in 1966. When first released, it had a gray phosphated finish, "Slimline" handguard, 8.9-inch barrel with "3-Lug" muzzle, and straight waffle magazines. Modernized improvements were introduced in the 1970s: proprietary "claw mount" rails for scope, laser, and flashlight attachments were introduced in 1973; un-ribbed curved magazines with chrome followers were introduced in 1977; the matte-black lacquered finish was introduced for export models also in 1977; and the polymer "Tropical" handguard was introduced in 1978.[28]
- MP5A1
- Standard MP5 with no stock and the "SEF" or "Navy" trigger group.[28][29]
- MP5A2
- Standard MP5 with a fixed stock and the "SEF" or "Navy" trigger group.[28]
- MP5A3
- Standard MP5 with a retractable stock and the "SEF" or "Navy" trigger group.[28]
- MP5A4
- Standard MP5 with a fixed stock, the "Navy 3-Round Burst" trigger group, and a straight pistol grip.[28]
- MP5A5
- Standard MP5 with a retractable stock, the "Navy 3-Round Burst" trigger group, and a straight pistol grip.[28]
- MP5SF
- Semi-automatic variant of the MP5 intended for the law enforcement and military markets, introduced in 1986 to meet a Federal Bureau of Investigation request for a "9mm semi-automatic carbine". Unlike the HK94, the semi-automatic MP5 variant for the civilian market, the MP5SF retains its standard 8.9-inch barrel. It has two variants: the MP5SFA2 with a fixed stock, and the MP5SFA3 with a retractable stock. It uses the "0-1" trigger group, but since 1991, it has been delivered with select-fire bolt carriers that make it capable of automatic fire if paired with an appropriate trigger group.[30]
- MP5PT
- Training variants of the MP5A4 and MP5A5. They are designed to use a plastic 9×19mm round developed by Dynamit Nobel.[31]
- MP5N
- Naval variant of the MP5, introduced in 1986 to meet a United States Navy request for a submachine gun effective aboard ships and in low-light conditions. It is essentially an MP5A3 with a retractable stock, "Navy 2-Round Burst" trigger group, tritium illuminated sights, and a custom "3-Lug" muzzle derivative for mounting a stainless steel suppressor produced by Knight's Armament Company (KAC).[25]
- MP5F
- Improved French variant of the MP5, introduced in 1999 to meet a French National Gendarmerie request for a suitable standard-issue submachine gun. It is essentially a modified and improved MP5A3, featuring a padded retractable stock, "Navy" trigger group, ambidextrous sling mounts, and internal improvements to handle high-pressure ammunition.[25]
- MP5 Mid Life Improvement (MLI)
- Modernized refresh of the MP5, introduced in 2015. It is based on the MP5A5 and features the MP5F's padded retractable stock, triple-rail "Slimline" handguard, "Navy 3-Round Burst" trigger group, quick-release sight mount or sight rail, and a RAL 8000 finish. Compatible components of the MP5 MLI can be switched out and retrofitted with other compatible MP5 variants.[32]
MP5SD
The MP5SD ("SD" meaning Schalldämpfer, German for "sound suppressor") is a variant of the MP5 with an integral suppressor, introduced in 1974.[33] 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.[34] 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 700 rounds per minute,[35] and is intended to use subsonic ammunition with the suppressor on at all times, though it can be detached.[24]
- MP5SD1
- Standard MP5SD with no stock and the "SEF" or "Navy" trigger group.[33]
- MP5SD2
- Standard MP5SD with a fixed stock and the "SEF" or "Navy" trigger group.[33]
- MP5SD3
- Standard MP5SD with a retractable stock and the "SEF" or "Navy" trigger group.[33]
- MP5SD4
- Standard MP5SD with no stock and the "SEF" or "Navy" trigger group. It is largely similar to the MP5SD1.[33]
- MP5SD5
- Standard MP5SD with a fixed stock and the "Navy 3-Round Burst" trigger group.[36]
- MP5SD6
- Standard MP5SD with a retractable stock and the "Navy 3-Round Burst" trigger group.[36]
- MP5SDN-1
- Naval variant of the MP5SD, with a retractable stock, the "Navy 2-Round Burst" trigger group, and the MP5N's KAC stainless steel suppressor.[36]
- MP5SDN-2
- Naval variant of the MP5SD, with a fixed stock, the "Navy 2-Round Burst" trigger group, and the MP5N's KAC stainless steel suppressor.[36]
MP5K
The MP5K ("K" meaning Kurz, German for "short") is a redesigned compact variant of the MP5, introduced in 1976. Developed from the stockless MP5A1,[29] 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.[25]
- MP5K Prototype
- Stockless, cut-down MP5A2 with regular iron sights and an open vertical foregrip, developed in 1976.[29]
- MP5KA1
- Standard MP5K with the "SEF" trigger group, smooth upper surface, and small low-profile iron sights.[25]
- MP5KA4
- Standard MP5K with the "Navy 3-Round Burst" trigger group and regular iron sights.[25]
- MP5KA5
- Standard MP5K with the "Navy 3-Round Burst" trigger group, smooth upper surface, and small low-profile iron sights.[25]
- MP5K-N
- Naval variant of the MP5K, with the "Navy" trigger group and a custom "3-Lug" muzzle similar to that of the MP5N.[25]
- MP5K-PDW
- "Full-size" variant of the MP5K, introduced in 1991. It is designed to provide the benefits of the MP5K with the size and handling of a regular MP5, and is essentially a regular MP5K with a custom folding stock, "Navy" trigger group, and 5.5-inch barrel with a custom "3-Lug" muzzle similar to that of the MP5N but for a Qual-A-Tec suppressor. Despite its name, the MP5K-PDW is not a personal defense weapon, as it uses a handgun cartridge and not the sub-intermediate cartridges used by actual PDWs; rather, its name is derived from its intended use as a defense firearm for vehicle and aircraft crews.[36]
- MP5K Operational Briefcase
- Standard MP5K intended for use with the Spezialkoffer ("Special Case"), a custom briefcase built by Hofbauer GmbH with a modified claw mount for holding the MP5K, a firing port, and a trigger built into the briefcase handgrip, introduced in 1978. Intended for security details in close-range defense or suppressive fire situations, the MP5K Operational Briefcase uses a firing mechanism built into the briefcase to allow the MP5K to fire without taking time to remove it; however, it cannot be reloaded, cleared of obstructions, or emptied of spent shell casings without opening the briefcase and detaching the MP5K.[37]
- MP5K Special Bag
- Variant of the MP5K Operational Briefcase introduced around 1978, using a leather suitcase called the Spezialtasche ("Special Bag"). Instead of using the handgrip as a trigger, the Spezialtasche features a hidden opening that allows the user to discreetly reach into the bag and fire the MP5K directly.[37]
- MP5K Falling Case
- Variant of the MP5K Operational Briefcase introduced around 1978, using a detachable briefcase called the Zerfallkoffer ("Falling Case"). Instead of allowing the weapon to fire within the case, the Zerfallkoffer's handgrip and claw mount is designed to be quickly detached from the briefcase, "shedding" it and allowing the MP5K to be used normally with a carryhandle. The Zerfallkoffer is also compatible with the MP7.[37]
Rechambered variants
Though the MP5 is normally chambered in 9×19mm Parabellum, two variants and an unreleased kit existed that used different ammunition.[38]
- MP5/10
- MP5 chambered in 10mm Auto, introduced in 1992. It features either a fixed or retractable stock, the "Navy 2-Round Burst" trigger group, and the MP5N's custom "3-Lug" muzzle derivative and tritium illuminated sights. It includes a bolt hold-open device, which catches the bolt in its rear position when empty, and is released by pressing a lever on the left side of the receiver. It is fed by a custom 30-round translucent straight magazines.[36] The MP5/10 was discontinued in 2000, but HK still offers support and spare parts.[38]
- MP5/40
- MP5 chambered in .40 S&W, introduced in 1992. It has largely the same features and configuration options of the MP5/10, and is fed by similar 30-round translucent straight magazines, but uses the regular "Navy" trigger group (without the burst-fire selection).[39] The MP5/40 was discontinued in 2000, but HK still offers support and spare parts.[38]
- MP5 .22 LR
- MP5 chambered in .22 Long Rifle, introduced around 2021. It comes in two variants: the MP5 .22 LR Rifle, which resembles an MP5SD3 with a 16.1-inch barrel hidden by a faux "integral suppressor" barrel shroud; and the MP5 .22 LR Pistol, which resembles an MP5A1 or MP5A3 with an 8.5-inch barrel. Both variants use the "Tropical" handguard and the "0-1" trigger group. Like all civilian market MP5 variants, it is semi-automatic only.[40]
- MP5 .22 Long Rifle Rechambering Kit
- Rechambering kit to convert an MP5 to .22 Long Rifle, introduced in the early 1970s and discontinued at an indeterminate point. The kit consisted of a barrel insert, a bolt group, and two 20-round magazines, and was mostly sold to law enforcement agencies for training purposes by easing trainees inexperienced with the MP5 into learning handling techniques and firing practice without the high recoil and cost of 9×19mm rounds. The conversion reduced the MP5's rate of fire to 650 rounds per minute. It was ultimately replaced by the MP5 .22 LR in 2021.
- MP5 6.5x25mm Rechambering Kit
- Rechambering kit to convert an MP5 to 6.5×25mm CBJ, which was proposed in the 2000s but never released. It would have allowed an MP5 to be rechambered simply by switching its barrel.[41]
Civilian variants
- HK94
- Civilian market variant of the MP5, imported from 1983 to 1989 (with a one-off final order for the California Department of Corrections and Rehabilitation delivered in 1991). It has a 16.54-inch barrel, "0-1" trigger group, push-button magazine release (as opposed to the paddle magazine release on regular MP5s), and a straight pistol grip similar to that on the MP5A4 and MP5A5. It has two variants: the HK94A2 with a fixed stock, and the HK94A3 with a retractable stock. Optional accessories included a handguard-mounted foregrip and a ventilated barrel shroud. The HK94 was particularly popular as a prop in film and television productions of the era, and blank-firing HK94s with "chopped" 8.9-inch barrels and fake automatic conversions were often used as cost-effective MP5 stand-ins well into the 2010s.[31][42]
- HK94/SG-1
- Accurized sharpshooting variant of the HK94, introduced in 1985. It was designed and intended for marksman fire in situations and environments where precise handgun cartridge fire may be needed, such as dense urban areas and indoor environments like prisons. It has a fixed match stock with a rubber buttpad and an adjustable cheekpiece, a folding bipod, a flash hider, and a Leupold 6x telescopic sight. A PSG1-inspired aftermarket trigger pack was also produced, featuring a target pistol grip and match trigger. The HK94/SG-1 did not sell very well due to its niche role and poor performance—it had poor range, penetration, and stopping power, and its Leupold scope was calibrated for .223 Remington and not 9×19mm—and only 50 units were imported to the U.S., primarily to target shooters and firearm collectors.[43]
- SP89
- Civilian market variant of the MP5K, imported to the U.S. between 1989 and 1994. To comply with the National Firearms Act, the SP89 features a redesigned handguard that replaces the MP5K's built-in foregrip with an extended barrel shroud. Like all civilian market MP5 variants, it is semi-automatic only.[42]
- SP5K
- Modernized SP89 for the American civilian market, imported to the U.S. as a pistol in 2017. It largely resembles the SP89, with a redesigned extended barrel shroud and a top-mounted Picatinny rail for sights. Like all civilian market MP5 variants, it is semi-automatic only.[44]
- SP5
- Modernized civilian market variant of the MP5 introduced in 2019, replacing the HK94. It resembles an MP5A2 with an 8.8-inch barrel, MP5K-style threaded adaptor, "Tropical" handguard, "0-1" trigger group, paddle magazine release, fluted chamber, and the buyer's choice of fixed stock, retractable stock, or endcap.[45]
- SP5K-PDW
- Modernized civilian market variant of the MP5K introduced in 2019, replacing the SP5K. It resembles an MP5K without its handguard foregrip. Like all civilian market MP5 variants, it is semi-automatic only.[46]
Prototypes
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.
- HK54A1
- Prototype improvement of the HK54, designed for the U.S. Navy Naval Weapons Support Center Crane's (NWSC) Joint Service Small Arms Program (JSSAP) in 1980. It was essentially a refreshed ambidextrous MP5SD with a redesigned retractable stock and compatibility with a 50-round drum magazine. It was designed to be suitable for frogmen and paratroopers in any environment, and was thus also designed to be reliably functional in extreme temperatures and while wearing bulky gloves. HK's proposal for the HK54A1 noted it could be converted to .45 ACP if necessary. An unknown number were produced for testing purposes out of regular MP5 components. The HK54A1 was never properly developed for field use, but it met most JSSAP requirements, drawing the attention of the U.S. government and leading to the development of the SMG I and SMG II.[47]
- SMG I
- Prototype derived from the HK54A1, first developed for the JSSAP between 1982 and 1983. It was intended to spawn a "family" of modular all-purpose submachine guns. Unique for HK, the SMG I used a simple blowback operation with separate lower and upper receivers and an easy-to-remove 5.8-inch barrel with an integral suppressor. It had a boxy body with a retractable stock and a diagonal foregrip. A mechanical and hydraulic buffer in the backplate and a timing device in the stock reduced its rate of fire to a manageable 500 rounds per minute, roughly half that of the HK54A1. The rear iron sight, resembling that of the HK21E, allowed for adjustments based on wind, ammunition type, and sight elevation, and also featured indents to assist with close-range point shooting. The trigger included an add-on to be used with bulkier gloves such as mittens. Only 20 handmade examples were produced. The SMG I was tested by NWSC Crane in 1984 and proved promising, but several minor issues prompted the development of the SMG II.[47][48][49]
- SMG II
- Prototype derived from the SMG I, developed around 1985. It has a largely identical design but addresses the issues reported by NWSC Crane. Its combination of the MP5, MP5SD, and MP5K was made more clear: analogous to the MP5 by default, the addition of a custom suppressor made it akin to the MP5SD, and the removal of the suppressor and retractable stock converted it into an MP5K-like automatic pistol. The three-round burst fire setting returned from the HK54A1. Several components were made from plastic to reduce weight, while the over-engineered rear sight was abandoned for a simpler MP5-style sight. Uniquely, the SMG II had a gas cylinder in the handguard with a gas relief valve on the receiver, used to control round velocity and thus also sound: the "L" setting reduced the propellant gases to fire rounds below the speed of sound—and thus without the usual crack of supersonic projectiles—for almost silent suppressed fire, while the "H" setting used all available gas to fire rounds at full velocity for reliable unsuppressed fire. Other internal changes were made to reduce cost and simplify production and maintenance, but otherwise the SMG II was largely just an improvement of the SMG I. Like the SMG I, only 20 handmade examples were produced for testing by NWSC Crane. While the SMG II again proved promising, it was ultimately abandoned, not for budgetary or technical concerns, but simply due to the success of the regular MP5 and its derivatives, which were already popular enough with the U.S. Navy and all other potential customers to make a replacement unnecessary; HK ultimately developed the MP5N for the U.S. Navy instead. Allegedly, between 60 and 80 additional SMG IIs were secretly commissioned for an unidentified U.S. government agency, possibly a member of the U.S. Intelligence Community, where they were favored by their users, but the lack of spare parts and the gradual move to higher-caliber firearms for close-quarters combat led to all of them being retired and melted down for disposal some time around 1999. Technical knowledge from the SMG II and the concept of a universal submachine gun were later repurposed for the MP2000 prototype and the UMP.[47][48][50]
- MP5 PIP
- Prototype developed around the late 1980s and early 1990s. Very little is known about the MP5 PIP or why it was developed, but it had a boxier body resembling the later UMP, a shorter diagonal magazine, and the "flipper" charging handle later used on the G36. Only one non-functional wooden mockup was produced.[51]
- MP2000
- Prototype derived from the SMG II, developed in the 1990s. It somewhat resembled the SMG II and featured a propellant gas-based round velocity silencing system similar to that of the SMG II. It was presumably an attempted revival of the SMG II concept to replace the MP5 for the 21st century. It is an immediate predecessor of the UMP, which was ultimately marketed as such.[47]
Manufacturers
China: Norinco manufactures unlicensed copies of the MP5A4, as the NR-08[52] and NR-08A,[53] and the MP5A5, as the CS/LS3.[54]
Greece: Manufactured under license by Hellenic Defence Systems (EASEllinika Amyntika Systimata).[55]
India: Indian Ordnance Factory manufactures unlicensed copies of MP5A3, as the OFB Anamika 9mm.[56]
Iran: Manufactured under license by DIO as the Tondar (MP5A3) and Tondar Light (MP5K).[22]
Mexico: Manufactured under license by SEDENA.[57]
Pakistan: Manufactured under license by Pakistan Ordnance Factories[58] as the MP5P, POF4, and POF-5.[59][60]
Saudi Arabia: Manufactured under license by Al Kharj Arsenal and Military Industries Corporation.[61]
Sudan: Manufactured by Military Industry Corporation as the Tihraga (MP5A3), a clone of the Iranian Tondar.[62]
Switzerland: Manufactured under license by Brügger & Thomet.[54]
Turkey: Manufactured by MKEK.[63] Their trigger groups are marked: E (Safe), T (Semi-Auto) and S (Full Auto) instead of "SEF".
United Kingdom: Manufactured under license by Royal Small Arms Factory.[22]
Users
