MP5 - The Choice of a New Generation

by Peter G. Kokalis, Technical Editor for Soldier of Fortune Magazine

It dominates. Heckler & Koch's MP5 submachine gun is the undisputed choice of the vast majority of law enforcement Special Response Teams and military Spec Ops units throughout the non-communist world. It has been so for almost two decades. Slightly revised and re-chambered for the 10mm Auto and .40 S&W cartridges, in addition to the 9x19mm Parabellum round, it now stands poised to surge forward into even greater pre-eminence.

By definition a shoulder-fired, selective-fire weapon chambered for pistol-size cartridges, the submachine gun is moribund as a genre. It has been buried by the assault-rifle and no major military organization has adopted a submachine gun as standard issue since shortly after World War II. Nevertheless, it has attributes that appeal to SWAT teams and, when fitted with a sound suppressor, to specialized military units involved in clandestine operations.

Founded by Edmond Heckler, Alex Seidel and Theodore Koch, all former Mauser Werke employees, H&K commenced operations in 1948 in Oberndorf/Neckar as a manufacturer of sewing machine parts and gauges for the machine tool industry.

Initially equipped with the MI Garand rifle, the resurgent West German Bundeswehr moved in 1957 to the FN FAL, made in Belgium. Eventually, 350,000 of this German model, called the GI (for Gewehr, or rifle) were manufactured. The Germans were well pleased with the GI and approached FN for a license to manufacture the rifle in Germany. The Director-General of Fabrique Nationale, the late Rene' Laloux, refused and rudely insulted the German Ministry of Defense officials. The German government immediately contacted the European licensee for the Spanish CETME (Compania de Estudios Tecnicos de Materiales Especiales) rifle, which was NWM (Nederlandsche Wapen-En Munitiefabriek) in the Netherlands. An arms agreement was reached quickly.

NWM was to provide, in exclusivity, the Bundeswehr with 20mm ammunition, in return for which Germany was given a license to manufacture the CETME (called the G2). The West German government granted the contract to both Rheinmetall and Heckler & Koch. Rheinmetall removed themselves from the scene, as they were occupied with manufacture of the MG3 (7.62x 5 1 mm NATO version of the MG 42 GPMG ). H&K refined the design further and it was adopted by the Bundeswehr as the G3. The rest is a history of worldwide acceptance and success known to all.

The most salient feature of H&K's line of small arms is the delayed blowback, roller-locking system of operation. This method of operation first appeared in the StG 45M developed at the Mauser Werke in 1945. It was part of the continuing evolution of the assault rifle concept initiated by the MP 44.

After the war, a former Mauser engineer connected with the StG 45M project, Ludwig Vorgrimler, built two prototype rifles in France using this type of breech mechanism. Contrary to rumor, Herr Vorgrimler was not responsible for the roller-locked, but dismal, French A-AT 52 machine gun. Moving to Spain, Vorgrimler took up shop with CETME. By 1956 the CETME rifle was chambered for the 7.62x51mm NATO cartridge. In 1958 it was adopted by the Spanish Army, in a form equivalent to the early H&K G3, as the Model 58 assault rifle. A prior use of roller locking is found on the MG 42 machine gun. However, the MG 42 is recoil operated and gas assisted and fires from the open-bolt position.

The Heckler & Koch system weapons operate as follows: The bolt mechanism consists of two major components, the bolt head and the boIt carrier. Although referred to as locking rollers, the action is never totally locked. In the firing position, inclined surfaces on the locking piece within the bolt carrier lie between the two rollers on the bolt head and force them out into recesses in the barrel extension. After ignition, the rollers are cammed inward against the locking piece's inclined planes by rearward pressure on the bolt head. The bolt carrier's rearward velocity is four times that of the bolt head. After the bolt carrier has moved rearward 4mm, the rollers on the bolt head (which has moved only 1 mm) are completely in, pressure has dropped to the required levels of safety, and the two parts continue their backward movement together. Several years ago the MP5 bolt head was improved and strengthened to inhibit cracking. Unbeknown to most, the MP5 bolt carrier contains 32.5 grams of tungsten granules which serve as an anti-bounce device.

Only 19 stamping operations are required to fabricate the H&K system sheet-metal receiver. The receiver is grooved on each side to guide the bolt carrier and firmly seat the buttstock group. The barrel is press-fit and cross-pinned into the receiver. A tubular extension which lies above the barrel is welded to the receiver. It holds the cocking lever and the bolt carrier's forward extension. The retracting lever moves in a slot cut into the left side of this extension and can be held in the cocked position by a notch at the rear.

As the recoil spring is made of thick stock, cocking resistance on the MP5 is somewhat greater than that encountered on other submachine guns. The recoil-spring guide rod, attached to the rear of the bolt carrier, mates to a plastic buffer in the buttstock's end cap.

The trigger mechanism is similar in design to that used in the FN FAL. When set on "0," "S" (safe) or a white bullet in a rectangular box with an "X" superimposed over it, the selector lever's spindle prevents all upward movement of the sear and its nose cannot drop out of engagement with the hammer's notch.

When put on "1," "E" (einzeln = single) or a red bullet in a box, pulling the trigger will rotate the sear down and out of the hammer's notch. When the hammer rotates forward, the sear slips forward and its end drops down off a fixed step. In recoil, the hammer is rotated back by the bolt carrier and catches the sear's nose, pushing it back in contact with the fixed step. After the bolt closes again, the auto sear releases the hammer, which is then held by the sear. Releasing the trigger allows the tail end of the sear to rise and move onto the fixed step. Pulling the trigger again will repeat the process.

When the selector lever is set to "F" (full-auto), or seven red bullets in a long box open at the front end (implying infinity), its spindle allows the sear's tail to rise so high that the sear's nose does not engage the hammer notch at all. The hammer is thus held by the auto sear only. As soon as the bolt carrier moves completely forward the auto sear is released and the hammer set free.

Three-shot burst controls are also available. They consist of an intricate ratchet-counting device fitted to the trigger mechanism, which holds the sear off the hammer until the allotted number of rounds bave been fired. The device ensures that only the correct number of rounds are fired in a single burst and any interruption commences a new count. After each burst the trigger must be released to set the counter back to zero. Although the burst mechanism is reliable when maintained properly, it adds significantly to the number of parts in the trigger mechanism. Furthermore, it is in my opinion a superfluous feature on this weapon, as its 800-875 rpm cyclic rate permits experienced operators to fire two-shot bursts with ease. U.S. Navy SEAL Team 6 experienced a serious accident during a training session as a consequence of improper disassembly/assembly of the 3-shot trigger unit, and discarded this option.

There are now four trigger units available for the MP5 series. All have housings fabricated from a two-piece synthetic molding. The standard "SEF" group provides safe, semiauto and full-auto positions with a selector lever on the left side only. Its pistol grip has finger swells, while the others do not but are flared at the bottom in the front to prevent the firing hand from slipping downward. The so-called "U.S. Navy" group offers the same three positions but uses bullets rather than numbers or letters for markings and is ambidextrous (a selector lever on each side of the housing). There is also the ambidextrous, four-position, 3-shot burst group.

The MP5 SF (single fire) carbine's ambidextrous trigger group has only two settings and will fire only in semiautomatic (this foolishness at the behest of the FBI). In addition, a special selector lever and lockout key are available to prevent the "SEF" trigger group from firing in the full-auto mode. The selector lever on all of these trigger groups can easily be pushed downward with the thumb of the firing hand while retaining the correct firing grip. However, the lever cannot be rotated upward - back to safe - without shifting the operator's grip. This remains as the single legitimate ergonomic criticism of the entire Heckler & Koch series.

The first submachine gun based on this method of operation appeared in the early 1960s and was called the HK54. This early gun had a flip-type rear sight positioned forward over the magazine well. The barrel had cooling ribs and two lateral slots cut over the muzzle to serve as a compensator. The forearm had cooling slots cut into it and the bolt carrier was longer and heavier than current models.

By 1966 the Heckler & Koch submachine gun had emerged pretty much as we know it today and was renamed the MP5. The muzzle brake and cooling ribs were eliminated and three external lugs were placed near the muzzle, to accommodate a blank firing device, flash hider and grenade launchers of both the ballistite and bullet trap types. The rear sight was relocated to the aft portion of the receiver and became the rotary-aperture type associated with the H&K system in general.

It should noted that rotation of the rear sight on the MP5 will bring into view apertures of different diameter only. Elevation remains constant. Elevation adjustments are made by insertion of a special tool with two spring-loaded wedges into the rear sight cylinder, to engage two slots in the axis shaft which contain the spring-loaded catch bolts. When the catch bolts have been depressed, the sight cylinder can then be freely rotated around its threaded axis shaft in the desired direction. The tool also contains a Phillips-head screw driver used to loosen the lock screw and turn the windage adjusting screw.

Once zero adjustments have been performed there is little requirement for continued sight adjustment of a submahine gun. The well-protected front sight post is not adjustable. Best emloyed as a ghost ring, the largest rear aperture should be used at all times, except when engaging targets at longer ranges with semiautomatic fire. Self-luminous tritium front and rear sight inserts are available from H&K as an option or can be obtained from Innovative Weaponry Inc. (Dept. SOF, Suite 103, 337 Eubank, N.E., Albuquerque, NM 87123; phone: 800-334-3573).

MP5 submachine guns are available in a number of configurations. When equipped with only a plastic end cap with sling swivel, it is known as an MP5 A1. The MP5 A2 is fitted with a fixed buttstock. The MP5 A3 features a retractable stock. In 1976 the MP5K was introduced. Designed for clandestine operations, the barrel was shortened from 8.85 inches to only 4.5 inches. The tubular extension above the barrel was also shortened. A vertical fore-grip has been added and the bolt carrier shortened. There is usually no buttstock, only a receiver cap. A model in which the rear sight apertures have been replaced with fixed sight is called the MP5K A1. A side-folding (to the right) stock is now available for the MP5K and this enhances its hit probability significantly. When not fired from the shoulder, submachine guns have poor accuracy potential, except at very close ranges.

All MP5 stocks, except those designed for the MP5K series, are interchangeable. Although the fixed buttstock provides the most stable firing platform and is to be preferred, the MP5's retractable stock is among the best of this type. Rarely encountered, but available, the MP5 PT variant is a special training weapon designed to fire plastic ammunition only.

The MP5SD is the sound-suppressed version of the MP5. The barrel has been ported and surrounded by a tubular casing. Escaping gases are diverted through the barrel's ports to drop the bullet's velocity below the sonic level before it leaves the muzzle. The muzzle blast's sound level is drastically reduced by a helix within the casing, which increases the gas volume and decreases its temperature. While quiet and easy to maintain, the MP5SD drops the bullet's velocity so low that it will often fail to defeat body armor, as the wound ballistics potential is reduced to little more than that of a .380 ACP round. As a consequence, sound suppressors of the muzzle type (which do not degrade the projectile's velocity) are also frequently attached to a non-suppressed MP5 by means of the barrel's three lugs or by threading the muzzle.

A recent version, called the MP5K-PDW (Personal Defense Weapon), combines the MP5K with the side-folding stock and a muzzle-type sound suppressor originally designed by highly respected Mickey Finn of Qual-A-Tec. The barrel has been extended to 5 inches so as to include the three mounting lugs and threads for the suppressor. With the stock and suppressor, the total weight empty is 7.4 pounds. The cyclic rate is 900 rpm. Both shoulder and leg harnesses are available. It is intended to serve as a compact weapon for vehicle or aircraft crewmen, but has obvious applications for clandestine operations.

The exterior finish used on the H&K system is baked enamel. The exact hue has varied over time. Early H&K weapons were finished with a light charcoal-gray enamel. More recent specimens have a matte black finish.

MP5 magazines come in two capacities, 15- and 30-round. They are of the modern two-position feed tvpe. They are well-made entirely of steel, and the floor plate is held securely in place b two side tabs (although they are a bit more tedious to disassemble than more conventional designs). The original 30-round magazine was a straight, uncurved box with a plastic follower. Feed problems with some lots of ammunition encouraged a change in 1977 to a curved magazine with a chromed-steel follower.

MP5 magazines are not difficult to load by hand. However, an efficient - but classic example of the Teutonic obsession for over-engineering - magazine loader-unloader is available for those with limp wrists. Also offered is a clamp which holds two magazines. In use, it interferes somewhat with the left arm when firing the weapon.

Because of this weapon's closed-bolt method of operation only 29 rounds should be loaded, as MP5 magazines stuffed with 30 rounds will not always seat in the magazine-well if the bolt group is forward. Also, when the tactical situation permits, the operator should observe whether the top round was on the left or right of the staggered column prior to insertion and charging, and then remove the magazine to establish that the top round has moved over (indicating that round has been chambered).

Since the late 1970s, Heckler & Koch has employed a simple letter code marked on the top of the receiver, the bottom left side of all magazines and some components to indicate the year of manufacture. Given that "A" signifies zero, "B" means " 1 " and so on up to "J," which stands for "9," it's easy to date any H&K weapon or magazine. For example, a receiver marked "IF" tells us that the firearm was produced in 1985.

H&K introduced a.22LR conversion kit for the MP5 in 1970. This unit consists of a barrel insert, two 20-round magazines with plastic collars and a bolt group which replaces the MP5's single-coil recoil spring with two nested-coil springs. This latter modification reduces the cyclic rate to 650 rpm. But unfortunately the MP5 conversion kit is prone to continual stoppages. With every two or three magazines, an empty case will fail to extract and the bolt will travel rearward and then forward, stripping a another round from the magazine and attempting to chamber it. Sometimes this stoppage is easy to clear, but all too often the empty case or loaded cartridge will either wedge into some inconvenient location in the bolt group or drop down into the trigger group, requiring disassembly of the weapon.

As the MP5 .22LR conversion kits never performed in a totally satisfactory manner, series production ceased after no more than 300-400 were manufactured. Until five years ago, these kits were rarely, if ever, seen in the United States. In November 1987, 137 of these MP5 subcaliber conversion kits were obtained from a West German police agency and imported to the United States. They are of value to collectors only. All .22LR rimfire ammunition produces excessive fouling. In general, conversion kits of this type, designed for low-cost training, operate with only marginal reliability in selective-fire weapons.

While a standard European-style leather sling is available for the MP5, in my opinion the H&K web multi-purpose carrying sling is far superior. For years this sling was an enigma to me, as the H&K manuals do not adequately describe its installation and use. But once you solve the mystery of its employment, few other slings will satisfy you. To correctly install the H&K sling onto an MP5, first attach the sling's spring-loaded hook into the eyelet on the front sight base. Then install the rear swivel by means of its spring-clip onto the buttstock. Pass the sling through the rear swivel and with its end-buckle connect it to the plain end of the second segment of webbing, which has a steel double-loop (with a diagonal bar) at the other end. Hang the double-loop on the spring-loaded hook attached to the front sight base. In this configuration you have a normal carrying sling.

To convert the sling into a "ready"- position carrying mode, pull the double-loop down and over the spring-loaded hook, and attach it to the spring-clip riveted to the left side of the magazine-well. Put the rear portion of the sling over your left shoulder and around your back. The front half will rest across your chest. With the buckle, adjust the sling until the weapon rests across your chest in a "port arms" position with the muzzle tilted upward. Grab the pistol grip and forearm and push the weapon sharply forward. The double-loop will snap out of the spring-clip on the magazine-well. Simultaneously bring the weapon up into the firing position onto your shoulder.

Sometime after 1973, the MP5 receiver was altered to permit attachment of the standard H&K clamp-mount for optical equipment. This includes night vision units of the infrared or starlight varieties, and an aiming projector which emits an intense narrow beam of light along the line of fire, powered by a 55-watt halogen lamp. This latter device can be used to both locate and temporarily blind targets. Three conventional telescopic sights were available at one time or another: The Zeiss 1.5X-6X variable, the Schmidt & Bender 4X25 and the Hensoldt 4X24. The Zeiss scope is too bulky for use on a submachine gun, and Schmidt & Bender has gone out of business. The excellent Hensoldt 4-power scope's reticle pattern is that used by the German military since World War I. It consists of a single, thick pointed post at the bottom of the field of view with horizontal side bars and stadia lines. Although never popular in this country, this format excels in subdued light and offers faster target acquisition than standard crosshairs. However, no scope was ever dedicated to the MP5 and the 9mm Parabellum cartridge and the only one available is marked "HK 33." Its elevation drum is calibrated for the trajectory of the 5.56x45mm NATO M193 cartridge. I wouldn't recommend employment of a 9mm Parabellum submachine gun much beyond 100 meters in any event, and if zeroed for that distance, the 5.56x45mm-calibrated Hensoldt scope combined with the MP5's closed-bolt method of operation will enhance the hit probability on static targets at that range. But, 4-power scopes belong on neither burp guns nor assault rifles. The operator's field of view is too limited and acquisition of moving targets is difficult. Optical devices of this type should be restricted to dedicated sniper systems.

Laser sights can also be attached to the top of the MP5 receiver by means of the H&K clamp-mount or, in the case of the Pulse Beam Laser Sight available from H&K, to the end of the barrel. If these systems have been properly zeroed, when the laser dot is placed on the target, hit probability is quite high. However, in my opinion the usual trade-off is not acceptable. Operators invariably seek out the dot and instinctively react to place it on the target with no regard for the proper shooting stance or training which has mandated that they bring the weapon up to the shoulder and quickly apply a "flash front" sight picture to the target.

Under stress, we do what we were trained to do. If we shoot correctly in daylight, but become accustomed to sloppy techniques when a laser sight is employed in subdued light or indoors, when the party starts our brain will be forced to decide between two alternative firing techniques. That's bad. There simply isn't time for decision-making like this in a combat environment. Although much more expensive, night-vision equipment provides superior target discrimination and greater tactical potential than laser sights. Aimpoint-type sights were attached to MP5s employed by Spec Ops groups during Desert Storm. I don't endorse them either, as they are usually fragile, but they have more tactical applications and greater justification than lasers.

Everyone agrees that firing from the closed-bolt position offers inherently higher hit potential than that obtainable from submachine guns which fire from the open bolt. When the heavy bolts utilized by most pure blowback SMGs fly forward and then stop violently against the chamber, accuracy is bound to be adversely affected. The theoretical problem associated with closed-bolt operation has always been that of "cook-off." When barrel temperatures greater than 250 degrees Centigrade are maintained for more than a minute, premature ignition of a cartridge in the over-heated chamber becomes possible. There has been some speculation about the MP5 in this area.

In fact, you cannot induce cook-offs in the MP5 under any remotely realistic set of circumstances. However, the receiver's chamber area, which acts as a heat sink, gets righteously hot in the attempt. If you are accustomed to holding the palm of the support hand back against the magazine-well and under the chamber area, the larger (and now standard), so-called "tropical" forearm is recommended instead of the earlier slimline handguard.

Anotber forearm that I can recommend without reservations incorporates a quartz-halogen flashlight operated by a pressure tape switch on the right side. It can be turned on just long enough for positive, close-range target discrimination and acquisition at night. Manufactured by Laser Products and distributed by H&K, the Sure-Fire Model 628 tactical light is powered by a 6-volt lithium battery and provides the user with 15,000-candle power.

To no small extent, the MP5's amazing popularity is due to the number of configurations it can almost instantly be converted into and the vast quantity of accessories available for it. In addition to those already mentioned, there is a cleaning kit, chamber face-rod and brush, and both web, leather and rubberized canvas 3-magazine pouches. Both an attache-type hard case and soft leather briefcase are available for "007" types who employ the MP5K. A trigger lever on the attache case's carrying handle and an opening at the rear of the brief case permit firing the weapon while hidden within the cases in any position from the vertical to the horizontal - obviously at almost point-blank ranges only. Aftermarket products abound as well. One of the most useful of these latter items is a single-magazine pouch made by Bruce Nelson Combat Leather (Dept. SOF, P.O. Box 8691 CR]3, Tucson, AZ 85738 - catalog $3). Hand-precision molded to securely retain the MP5 magazine's curved contour, the magazine rides in this open pouch (worn on the weak side) with the floorplate facing down and the feed lips up. It provides an additional 29 rounds for undercover or surveillance operatives, and a full-flapped version is also available.

As the blowback action is retarded by the two locking rollers, a much lighter bolt assembly is possible. The MP5, with retractable buttstock and without magazine weighs only 5.6 pounds. The trade-off here is a higher cyclic rate, which varies from 800 to 875 rpm (depending upon the recoil impulse delivered by the ammunition employed) - but still below the level at which full-auto hit potential falls off sharply from excessive muzzle climb. In the semiautomatic mode, the MP5 series cannot be matched by any other submachine gun in accuracy potential.

The MP5 series is not particularly ammunition sensitive. It will digest any bullet weight and configuration available in 9x19mm Parabellum, including round nose, truncated cone and Jacketed Hollow Points (JHP) of almost every shape. In fact, the original Winchester subsonic 147-grain JHP round - variations of which are now derigueur throughout U.S. law enforcement agencies - was designed for use in the MP5SD. I have fired or observed firing of tens of thousands of rounds of every type of 9xl9mm ammunition imaginable through MP5 submachine guns. During the course of this I have encountered only two stoppages - both of the same type and both one-in-a-million occurrences.

This stoppage occurs when an empty case is extracted from the chamber and spins under the bolt carrier to wedge itself between the carrier and trigger group, instead of being propelled out the ejection port. Clearing this stoppage requires removal of the buttstock and swinging the trigger pack forward to expose the case. If this should occur during a firefight, your best alternative would be to discard the weapon and immediately transition to your handgun. Many of those familiar with the MP5 have heard of this stoppage, but few have ever seen it. Since it is rare and cannot be induced, no one knows for sure what initiates it, although most authorities surmise it might be the result of a weak extractor spring. MP5 extractor springs are copper colored, while those of the G3/HK33 are silver colored. Use of a rifle extractor spring in the MP5 can result in a failure of the bolt to go into battery. In contrast to most other designs, the H&K system employs "push"-type extraction, not "pull"-type extraction.

Newest members of the MP5 family are the MP5/10 and MP5/40, chambered for the 10mm Auto (both high and low impulse) and .40 S&W cartridges, respectively, and weighing 6.5 pounds empty. Several important new features have been added to these weapons. The lack of a hold-open device on the H&K weapons series has been criticized by some users. A spring-loaded, ribbed bolt catch (located on the left side of the receiver directly above the trigger pack) holds the MP5/10 and MP5/40 bolts to the rear after the last round is fired. Depressing the bolt-catch release lever permits the bolt group to travel forward and chamber the first round after a loaded magazine has been inserted. This will considerably increase the speed of tactical reloads as the bolt no longer has to be manually retracted to charge the weapon.

The sling clamp riveted to the left side of the magazine-well has been deleted and replaced with a fixture patterened after that of the prototype G41 rifle. It will appear on all future production series MP5 submachine guns. The magazine catch/release button on the right side of the receiver has also been omitted. The MP5/10s barrel is threaded to accept a sound suppressor and other muzzle devices. Its thread protector can be stowed in the pistol grip's hollow handle.

A newly designed translucent 30-round magazine allows the operator to see the immediate status of rounds remaining. These magazines snap together without the need of an accessory clamp, in a manner reminiscent of the Swiss SG 550/551 assault rifles. These uncurved, straight box-type magazines are made from a specially developed high-strength polymer that makes them 30% lighter and impervious to corrosion. There is the usual high degree of interchangeability of parts, accessories, stocks and slings between the MP5/10 and MP5/40 and 9x19mm MP5s. The 3-shot-burst trigger group is standard, but all of the other MP5 trigger groups are available as options.

Lightweight, innovatively designed, sturdily built, reliable, well balanced, continually improved and expanded, and surrounded by a large assemblage of useful accessories, the MP5 series will continue to warrant serious consideration by potential users well into the foreseeable future. MP5 series submachine guns are available to military and law enforcement agencies only. For further information write to Heckler & Koch, Inc. (Dept. SOF@ 21480 Pacific Boulevard, Sterling, VA 22170-8903; phone: 703-450-1900).

Other countries have manufactured the MP5 under license from Heckler & Koch for domestic use only. These include POF of Pakistan, MKE of Turkey and Saudi Arabia. Greece is apparently licensed for the MP5 but has never produced anything but lavish advertising brochures. Mexico will soon commence licensed series production of the MP5. Portugal, which manufactures the G3 rifle under license, has never applied for a license to produce the MP5. Licensees purchase a specific technical data package from H&K and thus their products do not reflect the modifications and improvements made over time at Oberndorf-Neckar.

This article first appeared in Fighting Firearms Magazine.