The first U.S. machine gun patent was issued to Samuel L. Farries of Middleton, Ohio in 1829. Eli Whitney progressed from his cotton gin invention, Samuel Colt started thinking full auto from the deck of a ship in international waters, John Browning (and his father) from a small workshop, and David (Carbine) Williams did it from a prison cell. All in the great American tradition of rugged individualism….

Once upon a time there were a handful of licensed firearms manufacturers (Class 02 SOT) who never reached the heights of Colt, Winchester, Remington, etc. Nor did they particularly aspire to. However, they played by the same rules, paid the same fees and taxes, held the same licenses, did the same paperwork and complied with the same baffling array of Federal, state and local laws. They were self-financed, self-employed, and self-driven. This cadre started a revolution in the early 1980s within the firearms community and some made a mark for themselves and their wares. They were a testimony to the classic American entrepreneur trying to build a better mousetrap. They daringly offered custom services to a marketplace that was closeted, secretive, largely ignorant and very, very small. That marketplace was what we call the NFA Community, or the Class 03 community. Good and bad, glad and sad, full of passion and insight, they climbed a mountain only to fall to the sea.

What these Knights did was full auto conversions on semiautomatic firearms. Specifically, they applied their own individual hands-on re-engineering techniques customized to a selection of firearms – some which have even escaped the most recent media-induced misnomer of “semiautomatic assault weapons.” Going where few had publicly dared go before; each had his unique handle on firearms technology. Each Knight figured out a conversion technique and refined it as best as a small production machine shop equipment would take them. Most had no training, or manuals, instructions or factory parts to work with. It was frequently seat-of-the-pants work.

Collectively we might call them “custom conversion military weapons experts,” which would be an over-simplification. Some may have been gunsmiths or armorers. Most were inventors. Some had military experience. Most had few real world credentials as firearms designers. But in reality, most could actually take a block of raw steel and cut away everything that didn’t look like a gun and it would shoot when they were done. Every conversion was an adventure and a new challenge. Largely, they had to re-invent the wheel. If parts were needed, they made them, often carving out the bits and pieces by hand. Later, molds were made to cast perfected sear designs or other pieces of their conversion techniques. Every customer had to be educated because they had forever been told, “All machine guns are illegal,” and all believed it. Everyone knew it was very, very, expensive. Except what our Knights were offering wasn’t.

Almost every collector and shooter could now have affordable rock n’ roll. What a concept – be still my heart! The start of my instructional talk to potential customers who were almost always misinformed went something like this: “If you don’t run dope, horses, or women, if you pay your taxes and back alimony, have been a good boy all your life and are not a known ne’er-do-well in your neck of the woods, you too can own one of these fine machine guns!”

Back in The Day, if you could sign a yellow (then) sheet Form 4473 and not lie to any of the questions and could get the local sheriff or police chief to sign the law enforcement section (not a certainty at all), could paste a photo on the Form 4 which didn’t make you look like a miscreant and could acquire a gun and the money to get it converted to full auto by one of the aforementioned Knights, then Yes! You could come to the party and bring your own fast gun and put out a heart-thumping, flame-spewing, put-hair-on-your-chest, singe your eyebrows and bloody your nose glorious exhibition of firepower.

These little no-name Knights had to be ferreted out. You had to know someone who knew someone who heard it from a guy at work, etc. When you finally stumbled across the threshold of their machine shops, usually hidden discreetly in out-of-the-way places, you were beside yourself with glee. You had entered the domain of genius, daring-do, and joyful noise.

Greeted by a test-firing rat-a-tat-tat staccato of 9mm or .223, you paused for breath and prayed you could get past the gnarly security barrier. Rarely did you encounter anyone other than The Man Himself. This fellow likely greeted you from across his lathe or from behind his milling machine hollering he’d “be with you in a minute.” Wiping his brow and hands on a greasy shop rag, he would shake your hand and ask what he could do for you. Oh, My! (Breathe slowly, please.)

In due course, you would hand over your AR-15, your sleek H&K, or maybe an Uzi or an AK type. Any one of three-dozen or so likely conversion candidates. Your investment was in steps: buy a gun, pay for the conversion, pay the tax stamp, and buy ammo & accessories. Workable money for most people. After months of anticipation and frequent high anxiety attacks, you would receive The Call. Your gun is ready, your paperwork has cleared, and yes, a case of ammo is being held for you. You had attained the headiest of all firearms acquisitions – your first NFA firearm.

Yes, there was almost always a second and a third, ad infinitum. Potato chips have nothing on these goodies for not being able to have just one. It wasn’t about addiction. It was the unending thrills …of the hunt, of successfully negotiating the morass of lawful acquisition, the expenditure of significant monies from a working man’s budget, the lawful ownership of that which many people aspire to and would never obtain, and the lawful and necessary commitment to becoming the ultimate gun owner. Thrill-seekers abound, because you got to shoot it!

Our motley Knights did not have the support of the firearms industry, nor of the proclaimed “traditional” gun owning public. (Yes, you surely detect my aggrieved sneer at the memory of those who looked away with distain. They didn’t “get it” about how important it is for Americans to own military firearms… Bless their hearts.) Many Americans including “traditional” gun owners just refuse to understand that the Second Amendment outlines that Americans have a citizenship duty to come to the defense of the nation, bearing the arms of the day (i.e. military weapons being used by the military of our times. See: M1, M14, M16.). Furthermore, we are to be fully equipped to take care of business and be fully trained. That’s not something you do after 3 days at boot camp with the first real gun you ever saw. Our Freedoms in the First Amendment stand on the shoulders of the Second. Without adherence and exercise of the Second, we got diddily, friends. Our American Republic becomes a toothless on-paper-only tiger and we can only cower under our beds and hope nobody wants a piece of us. While the idea of making these conversions and owning them in the early 1980s is discussed as “fun,” the fact is that martial enthusiasts have always coincided with free, strong populations.

The Knights weren’t schlepping hunting guns, or shiny engraved collectibles, or respectable vintage 6-shooters. What they worked on had mostly black finishes, often less than perfectly manufactured (to the point of ugly); and were the semi-auto civilian versions of business guns. Not even that mighty behemoth, the NRA, acknowledged either the converted guns or the Knights’ existence, until much later when forced to acknowledge their contributions …both good and bad.

In May 1986, the infamous statute 922(o) of the McClure-Volkmer Firearms Owners Protection Act took all the fun out of it. The door that was slammed closed hit the collective noses of future NFA would-be owners. (And undermined, desecrated and negated the Second Amendment for what has seemed like an eternity.)

The Knights of the Black ‘N Ugly Armories created some of BATF’s worst nightmares. They managed to “paper” some of the oddest items… as there were few rulings on what made each particular firearm an NFA weapon. BATF had to make it up as things rolled along as new techniques reared their ugly heads. Mired in a morass of arcane and hard to understand laws created by our elected representatives, filtered through decades of regulatory rulings and assorted confusing muck, the BATF and the NFA manufacturers were frequently adrift in uncharted waters. Various Class 02s declared everything from a shoelace used to convert a Mini-14 to buckets of unfinished FA sears as “machine guns.” There were few firearms experts at BATF and frequently they had to accept the word of the 02 manufacturers as to what made a particular gun a machine gun. Some items were papered simply to protect the 02 from possible BATF adverse action. If an 02 deigned to declare a gum wrapper or piece of tin foil as an NFA weapon, BATF had to accept it as such. This was not the free ride it sounds like. Conversely, if it could be used to do the deed, you had to paper it or risk the consequences of committing an illegal act. There was bickering, squabbling, hassles and the occasional integrity issue to be dealt with. No industry support and no free legal backup protection or rights organization protecting Class 03 were available. Some Knights knew what they were doing, some were wily, some were very good at their inventiveness, and some were butchers.

Collectively, our Knights produced tens of thousands of affordable, shootable, NFA Class 03 guns and hardware. Class 03’s will never be boring, same-same, or cheap to shoot. Once upon a time, these were cheap(er) to own. Now, alas, it is a rich man’s hobby. Due to the unholy aberration in 1986: Pioneering… MIA. Expertise… aging. Availability… mostly gone into some collector’s “Black Hole” – that’s “where guns go in and don’t come out.” Affordability… get serious. This is the laugh that hurts.

From our Knights came forth ingenuity and invention, progress and new design. They did everything the hard way. They sacrificed and they pioneered. Nobody financed the R&D. Projects gone awry, mistakes, false starts, dead ends, and losses were absorbed by them, not some giant conglomerate owned by foreign investors. They got their hands dirty and rarely made any real money for themselves. They crossed the lines drawn in the sand. They stood against the tide. Each Knight was on his own. As independent thinkers and doers, it should make it hard to throw stones at them now, yet people do.

I am no sideline observer to all of this. I can claim to be an eyewitness, a participant, a supporter, and a partner. I have labored on the Class 02/03 line since 1982. From the firing line, I occasionally still dance with the one that brung me, an RPB SMG M-1l/.380 ACP. I have shot more than my share of all kinds of guns. Trust me; cold dead fingers are not very useful with any of them. However, I submit to you that if it’s not black n’ ugly, 850 RPM or more with an 8 pound trigger pull, it’s not real shooting!

So if you own an NFA firearm or even its semi-auto counterpart, you likely need to thank the small, mostly unknown and unlauded, Class 02 Licensee. These are folks who carry the American Warrior Spirit within and forward. I applaud our modern Knights who are responsible for keeping faith with the Second Amendment and using their expertise, skills and talents to progress forward firearms technology, our military might and our civilian readiness. They are indeed the real traditionalists.

(Linda and the late J. D. Farmer, Jr. worked together as Hard Times Armory, Inc. now in Kennesaw, GA. Converting a considerable selection of semi-autos to NFA select-fires and producing suppressor and silencer designs, Mr. Farmer was the plaintiff in Farmer vs. Higgins seeking to overturn the 1986 ban. Linda remains in the business and continues to be infamous for her opinions.)

By Jim Schatz

In April of 1980 Heckler & Koch responded to solicitation number N00164-80-R-0052 from the Naval Weapons Support Center (NWSC) located in Crane, Indian for the design and fabrication of a Joint Service Submachine, then referred to as the JSSAP Gun. This advanced new 9mm submachine gun was developed for the U.S. Armed Services under the established usr requirements compiled by the Joint Service Small Arms Program (JSSAP) office. The JSSAP gun was intended to bring a modern submachine gun into the ranks of military units, especially those special operations units tasked with close quarters battle in anti-terrorist and hostage rescue missions. Heckler & Koch’s involvement in this program brought about a family of unique submachine guns that would never actually enter series production. However, this does not mean they were not used operationally. A handful of well positioned readers can attest to this fact and many informed experts claim the 9mm submachine gun the Heckler & Koch “SMG” as it would be called, may have been the world’s most flexible smg even today.

Background. An unfilled tactical need arises.

Submachine guns, while used extensively in most of the major conflicts of this century, in many ways were never taken seriously by frontline military personnel. In most cases smg’s like the M3 “Greasegun” and Thompson were utilized as bullet hoses for close range engagements and were often carried by heavy weapon crewmen, unit leaders, armored vehicle personnel, MP’s, etc.- those persons unable or unwilling to carry the full size service rifle of the day. Having said this, the submachine gun has always had its own niche in special “commando” units requiring greater firepower and portability in exchange for reduced combat range.

With the advent of modern terrorism in the 1970’s and the propensity of “T’s” to take hostages in confined spaces like aircraft, buses, ships and buildings the popularity of the submachine rebounded. This is partially due to the sub gun’s quick handling characteristics in tight spaces, diminutive size, reduced range and the hazards to innocents afforded by the pistol caliber cartridges these weapons characteristically fire. The success of the German GSG 9 rescue of hostages held on a Lufthansa airliner in Mogadishu, Somalia in October 1977, and later the highly publicized hostage rescue at the Iranian Embassy in London in May of 1980 by the British SAS put the smg on the map the modern world to see.

The right tool for the job

Any auto mechanic or surgeon knows that it takes more than one instrument to perform a given procedure or operation. This same rule holds true in the world of armed combat. An assault rifle is not always the best weapon for the task at hand, nor is a handgun. In the 1970’s and even today, the inventories of the world’s most elite special units are comprised of a host of small arms that can be drawn from by the operator for the specific mission.

The world-renowned MP5 submachine gun is used by more elite military and police units in the world than any other weapon of its type. By 1980 more than 500,000 MP5’s had already been produced and fielded in countless countries around the world. Units like GSG 9, the British Special Air Service and America’s own Delta Force and SEAL’s teams make all three of the MP5 models available to their shooters for any given mission that may arise. The full size MP5A3 with retractable buttstock and its many variants is the workhorse, responsible for most of the CQB and protection work. However if you’re a climber, swimmer, pilot or the first guy into the breach, you may need one hand free to perform other tasks. In this case the stockless MP5K is a far better choice as it allows for acceptable full auto fire at close ranges with one hand. Although to effectively fire a 4 1/2 pound machine pistol with a cyclic rate of fire of 900 rounds per minutes does require a great deal of practice and acquired skill. For times where the covert engagement of a target is required or where the reduction of muzzle flash in explosive environments is an absolute must, a sound suppressed submachine gun, like the HK MP5SD, is often the first choice. Wouldn’t it be great if all of the capabilities were available in one gun? Enter the SMG.

The JSSAP Gun. Enter the HK54A1

The general concept and goal of the U.S. program was to challenge the industry to create a modular or “family” submachine gun that could be reconfigured by the operator without tools to perform the missions of all three MP5 models described above. Not only would this reduce the sheer number of weapons within a unit but the “one gun does all” concept would insure that the right gun is on station when needed. The level of proficiency can also be elevated to new heights when the shooter need only train with one sub gun and not three. A cost savings? Yes, but in most cases during the past 25 years the cost of equipment and weapons and funding for their procurement was of little or no issue to the elite units of the world. The shooters from the world’s best anti-terrorist and hostage rescue units expend more ammo and ordnance in just one month than the purchase cost of the weapon through which the rounds are fired.

The HK54A1 and the SMG’s that would follow it had to be deployable in all operational and environmental conditions found around the globe. The weapon had to function reliably in temperatures ranging from 140 degrees F to -50 degrees F. The JSSAP Guns were to be carried into combat by swimmers and high altitude parachutists and be fully functional upon arrival. All parts were to be fully interchangeable and supportable by current levels of maintenance. The weapon and sound suppressor were to have a minimal service life of 10,000 rounds, fire in all attitudes (up, down, even sideways) and direct no propellant gas “blowback” into the shooter’s face during operation. In the sound suppressed mode it should be impossible to discern the visual “flash” and the report or mechanical noise of the weapon beyond 30 meters and provide at least 30 dB sound reduction when fired in the sound suppressed mode. The HK54A1 was to be accurate enough to allow first round hits on an E-type kneeling silhouette target at 100 meters with iron sights.

Using their protocol for assigning acronyms internally, HK calls the MP5 the HK54 (5 for submachine gun, 4 for caliber 9X19mm Luger) even today some 35 years after the first gun rolled out of the stamping presses in Oberndorf. The MP5 designation was one assigned by the German government when it adopted the weapon for governmental use. The A1 suffix denotes the modifications incorporated into the basic HK54 to meet the technical and performance requirements of the JSSAP solicitation. For about $180,000 of Uncle Sam’s money, HK designed and produced fully tested hand-built HK54A1 prototypes to prove the concept of the JSSAP Gun. Actually HK spent a great deal of its own IR&D funds on the initial design and testing of the HK54A1 prior to the release of the competitive JSSAP solicitation in 1980.

The HK54A1 pictured herein looks very much like the MP5SD we know today. In an attempt to use available production tooling and MP5 parts the “A1” was essentially a product-improved MP5 and little more. It was certainly a gun far too large and cumbersome to be used in the one handed role of the MP5K. The weapon was a delayed blowback operated submachine gun using HK’s famous roller locking system chambered for the widely available 9X19mm Luger cartridge. (It is interesting to note in HK’s proposal to the USG that it was mentioned that “the HK54A1 could be converted to caliber .45 ACP if required”). The 7-pound weapon with retractable buttstock included an integral sound suppressor, a 3-round burst mode, which can be fired at a sustained rate of 1,000 rounds per minute. Unique features of the HK54A1 included the means for the operator to selectively vent propellant gases from the ported barrel in order to reduce the velocity of supersonic ammunition below the subsonic threshold (1,088 fps at sea level) and for suppressed fire without the need for special subsonic ammunition not always available “away from home”. The HK54A1 could utilize a 30-round stick magazine but was also designed to use low profile 50-round drum magazines for increased “firepower”. A forward assist for silent loading, a bolt catch to hold the bolt open on the last round fired, an ambidextrous magazine release lever in the trigger guard, an ambidextrous safety/selector lever and sling mounting points made the weapon usable for left and right handed shooters.

A unique bolt lock positioned on the trigger group beyond the sustained fire position locked the bolt in a forward position to prevent movement of the bolt and thus offered the user nearly silent operation. The A1 had adjustable tritium sights and a hinged trigger guard to allow firing while wearing heavy cold weather or diving gloves. Complete specifications of the HK54A1 are included in the Comparison Table accompanying this article.

With all of it’s unique features, the HK54A1 was still produced mainly from stamped, folded and welded sheet steel like most HK’s of the day. While not perfect for the intended roles of the JSSAP Gun the HK54A1 met most of the operational requirements listed above and thus caught the attention of the U.S. Government. This successful demonstration of the weapon’s performance and HK’s abilities to meet difficult technical challenges led to a fully funded R&D program for the “SMG” in 1983 after a second proposal was submitted to the NWSC Crane in February.

SMG

While there were various models of the first SMG prototype with different features, the basic SMG was a 9mm weapon with semi and fully automatic modes of fire, a removable retractable buttstock and a threaded barrel for a removable sound suppressor. Without the buttstock the SMG was less than 14 inches in overall length and weighed 6.70 pounds unloaded without a magazine. This placed the SMG only slightly closer to the size and weight of the stockless MP5K (at 12.8 inches long and 4.40 pounds) than the full size MP5A3. Thus the goal of building a one-gun-does-all modular “family” submachine gun was at least partially achieved with the basic layout of the new SMG design.

Like the HK54A1 that came before it, the SMG was produced mainly from sheet metal components except the pistol grip and vertical foregrip. The weapon fired from a closed bolt but unlocked breech, a departure from the delayed blowback roller-locked bolt of the MP5 and HK54A1 that came before it. A notable departure for HK was the use of a simple blowback operation in the SMG. This was an attempt to reduce the complexity and cost of the weapon. The SMG was comprised of a lower receiver and a separate upper receiver with a user removable barrel. Using a simple barrel wrench to unscrew the locking nut this fundamental change represented an important departure for an HK long gun where barrels were usually pressed and pinned in place and considered a factory job to remove or replace.

A combination mechanical (spring) and hydraulic buffer reside in the removable backplate and, along with a “timing device” incorporated in the trigger group, help reduce the rate of fire of the SMG to a more manageable 500 rounds per minute – one half that of the HK54A1 “bullet hose”. The rectangular one-piece machined metal bolt assembly contains an inertia firing pin which can be disassembled for cleaning as well as a firing pin safety to prevent the firing pin from reaching the chambered round during rough handling or drops. A fixed but oversized trigger guard provides ample room for gloved fingers and the trigger can accommodate an add-on winter trigger for times where mittens are preferred over gloves.

The curved double column magazine for the SMG is produced from folded sheet metal and provides a capacity of 30 rounds. Ambidextrous operating controls abound on the SMG. The unique centrally located cocking handle, similar in design and location as that found on the Thompson or UZI submachine guns, reciprocates with the bolt and could be used to lock the bolt open or to release the open bolt by simply rotating the cocking handle 90 degrees. Two adjacent square buttons, located rearward of the magazine well on the plastic pistol grip, act as ambidextrous bolt catch release (top) and magazine release (bottom). The texturing of the two buttons is different to provide the user with a tactile feel to differentiate between the two controls during “blind” actuation of these buttons. These controls are very well positioned on the weapon allowing actuation with the non-firing thumb or firing index finger without wasted motion of the hands.

The ambidextrous combined safety/selector lever is typical of the HK MP5 but is positioned for easy reach and rotation into the firing modes without having to adjust the firing grip. A forward assist for silent loading (without letting the bolt slam forward) is provided on the SMG on the receiver above the right side safety/selector lever. The sliding buttstock with a hard plastic contoured buttplate can be retracted, extended or completely removed from the receiver simply by depressing a round button protruding behind the rear sight assembly. Ambidextrous sling attachment points for the typical and much copied HK multi-purpose combat carrying sling are provided on both sides of the receiver.

The sights of the SMG are extremely interesting if not overly complicated for a pistol caliber submachine gun. While weapon number 006 pictured in this article does not contain a gas relief valve for reducing the velocity of supersonic ammunition to subsonic levels, the weapon is set up to utilize both types of ammunition. The front sight is the stereotypical HK round hood with a fixed tritium dot front sight post inside.

The rear sight is in itself a technical marvel. A single peep aperture positioned on an elevating ladder is flanked by a pair of “Betalite” (tritium) capsules providing the user with an effective “3-dot” arrangement. The rear sight is sandwiched between two drums, obviously inspired by the design of the HK21E machine gun rear sight. The drum to the left is used to make course windage adjustments and requires no tools to do so. The right drum is actually two concentric drums, one inside the other. The outer drum is pushed inward onto a caming surface calibrated for the flight profile of supersonic 124-grain NATO ball ammunition. When the outer drum is pulled to the right, a different caming surface within the sight assembly adjusts the height of the rear sight for the different trajectory of subsonic ammunition. The elevation drum is marked for ranges from 25 to 150 meters and even has an “M” position that grossly elevates the rear sight aperture by nearly one full inch. In this position the line of sight is raised for firing the weapon wearing a gas mask, protective equipment which prevents the shooter from establishing a normal and proper cheekweld on the forks of the buttstock. (Note: When using the M setting the range is established for 25 yards and closer. The top of the front sight hood serves as a rough front sight “post”). Both rear sight drums provide tactile indents to allow the user to “find” the 25-meter setting without the need to look at the sight. The rear sight can also be battlesight zeroed using nothing more than a Phillips head screwdriver. As if the SMG’s iron sight arrangement was not enough, the weapon also incorporates two welded scope mounting platforms that allow a scope or reflex sight to be quickly attached to the weapon by means of an HK scope mount shorter than but similar to that used on the HK21E and MSG90 sniper rifle.

The sound suppressor for the SMG actually has two different designs. Both are sealed units with metal baffles of “wipeless” design. Both suppressors encompass the barrel via a tubular extension and are secured to the weapon via the threads located around the base of the short 5.8-inch barrel. An aluminum sound suppressor from HK, basically a variation of the MP5SD suppressor, was developed for the SMG as was a far heavier stainless steel sound suppressor employing more advanced-machined steel baffles designed by Mickey Finn.

Numerous samples of the SMG were delivered to the Naval Weapons Support Center in Crane Indiana in 1984 for complete and extensive testing. Though minor problems were encountered, the overall performance of the SMG was very good indeed. It was the conclusion of the final test report that with minor changes prior to production, the SMG would serve well the special operators in the U.S. who needed the capability of three submachine guns in one tactically flexible weapon. HK was informed of the desired changes and shortcomings of the SMG and was asked to produce additional test samples for further testing. In 1985 HK delivered the new and improved SMG II to Crane.

SMG II. Twice as good?

Thinking back to the original design goal of the JSSAP Gun described earlier in this article, the SMG and to a greater extent the HK54A1 did not fully meet these requirements. Clearly, as is the case with most new hardware developments – cars, VCR’s and computers – it simply takes repeated design, prototype fabrication, testing, rework and retesting to optimize a mechanical device such as a firearm from prototype to finished product. The SMG II incorporated all of the ideas, changes and corrections deemed necessary by the testers and actual users involved in the JSSAP program testing. The SMG II became the modular one-gun-does-all submachine gun for which the program set out to obtain.

With the SMG II, the basic model with a retractable buttstock and without a sound suppressor is a 14-inch long weapon – a full 7 inches shorter than the MP5A3. By simply adding a sound suppressor to the basic weapon, the operator could create an “MP5SD” from the same platform. For missions where a small one-handed “MP5K” was required, the sound suppressor and buttstock were removed and the “telephone booth clearing” full auto SMG II “pistol” was created by the operator in the field or in route to the target.

The SMG II being based on the SMG was very similar in operation and design though there were a number of important changes and additions. To reduce the weight and production cost of the weapon, the magazine, backplate and entire lower receiver were produced from plastic. The 3-round burst mode of the HK54A1 had returned in the SMG II, as did the gas relief valve. Located on the receiver just forward of the flared magazine well this lever had two positions, “L” for low and “H” for high. Pulling out the front captured locking pin and sliding the plastic vertical foregrip forward off of the receiver revealed a small gas cylinder mounted parallel with and under the barrel that resembles the CO2 cartridges commonly used in airguns. When the gas relief valve was set in the “L” position a port opened in the barrel that allowed a measured amount of propellant gases to escape into this “holding tank”. By diverting this gas away from behind the projectile in the bore the exit velocity of the projectile is effectively lowered. A supersonic ball round fired in the SMG II with the gas port open departed the weapon below the speed of sound and thus eliminated the telltale “crack” of a supersonic projectile. Once the projectile left the bore in route to the target the gas remaining within the cylinder exits from the muzzle.

When the gas relief valve is placed in the “H” position the gas port is closed and all available gas is used to propel the projectile to the target at full velocity. This setting was used when firing subsonic ammo, when the sound suppressor was not being used or where the maximum terminal energy of the projectile on target was the primary concern of the user. Thus, unlike the MP5SD and HK54A1, the SMG II could be fired with or without the sound suppressor attached and used effectively with supersonic or subsonic ammunition with just the flick of a switch. It is interesting to point out at this point that the bolt lock feature of the HK54A1 was dropped from both of the SMG models because it did not reduce the sound signature of the weapon beyond a level provided by the sound suppressor. In other words beyond 30 meters the mechanical noise of the bolt was less than the noise of the departing projectile and escaping residual gases. Eliminating this feature lessened the complexity of the weapon and thus its cost. It also insured the user always had an immediate second shot available should the first round fired with the bolt lock engaged not perform as intended on its target.

One of the more noticeable changes from the SMG to the SMG II was the rear sight. Gone was the over-engineered and unnecessarily complicated rear sight. In its place the HK designers mounted the proven MP5 diopter rear sight assembly but added two tritium dots to the ears of the rear sight base for low light use in conjunction with the front tritium sight. While functional many American shooters found the sight line too low to use comfortably, unable to push the face far enough down on the stock to properly align the sights.

A spring détente was added to the receiver to prevent the sound suppressor from turning loose during firing and the three locking pins in the SMG II were retained in much the same way as the captured receiver pins of the U.S. M16 rifle to prevent loss. Other than minor changes made to facilitate production and durability, the SMG and SMG II were for the most part identical.

A better mousetrap? So where are the guns?

There were less than 20 SMG’s and 20 SMG II’s made in the 1980’s as part of the JSSAP program, each one basically a handmade prototype. At the conclusion of all this testing, the potential users, especially the Navy Special Warfare community, had already acquired a quantity of MP5’s after being introduced to the merits of the gun by foreign users such as the SAS and GSG 9. When it was time to ante up and procure sub guns, most users opted to stay with and purchase additional MP5’s rather than the SMG II. It was in 1986 that HK developed the “Navy” specific or “N” model MP5-N, MP5SD-N and MP5K-N for the Navy SEAL and SDV teams and Special Boat Units. Navy model MP5’s and variations of the basic MP5 were adopted by most of this nation’s military and law enforcement special units. The combination of little or no interest in a submachine gun for conventional military units and a less than enthusiastic demand from the spec ops community for the SMG II meant the gun was destined to go nowhere fast. Or did it?

A particular American organization, which will remain nameless, saw the tactical advantage of the one-gun-does-all concept that the SMG II offered, approached HK about building sixty SMG II’s for operational deployment. It did not appear that the gun would enter a series production so sixty SMG II’s were fabricated by HK as handmade prototypes at a unit cost of @ $2,800 each. Up until two years ago, these weapons were still in operational use and well liked by the shooters. However the chronic lack of availability of spare parts for the guns and the move to 5.56mm weapons for the CQB role, which was once the exclusive domain of the submachine gun, forced the weapons into mothballs and ultimately into the smelter.

Shooting the SMG

The accuracy of the SMG is on par with that of the basic MP5. The controllability of the MP5 in bursts longer than 3 rounds is hard to beat. Though the standard vertical foregrip of the SMG helps control the weapon in sustained fire, the delayed blowback roller-locked bolt system employed in the MP5 is believed by many to help reduce the felt recoil of the weapon and thus make it easier to control the weapon in long bursts. This may be true to an extent but one would also have to consider the longer length of the MP5, its barrel and sight radius as features that make the MP5 simply “feel” more controllable to fire in the sustained fire mode. The fact is when timed and firing short bursts, the results on the target – round placement and group size – between the roller-locked MP5 and the simple blowback operated weapons like the SMG are generally indistinguishable. The rate reduction system in the SMG II which reduces the cyclic rate of fire to @ 500 rounds per minute certainly aids in the weapon’s sustained fire control.

Firing the weapon in the fully automatic mode of fire with one hand, like the MP5K or any machine pistol for that matter, is difficult and down right ineffective as far as hits are concerned beyond engagement ranges of 20 yards or more. However, it is the range band from one side of an airliner or bus to the other wherein the MP5K model or stockless SMG II would reign supreme.

The well-designed and positioned operating controls of the SMG II are a plus to ease and speed reloads. The low sight line of the SMG II makes it all but impossible to fire the weapon using the iron sights. Using the optical sight on the HK QD mount solves that problem. Firing the weapon suppressed, especially left handed, is somewhat disconcerting due to the amount of gas blowback from the ejection port. The use of goggles eliminates this as a concern however. Reliability, as in all HK’s, is excellent.

Nothing ventured nothing gained

While HK’s hopes to get the SMG type-classified in the U.S. military and produced at their new Chantilly Virginia production site all but evaporated at the close of the JSSAP program in the mid-1980’s, the money spent by HK and the lessons learned were not in vain. In the late 1980’s HK had continued work on the “family” sub gun concept to the point where the SMG II’s successor, and the new UMP’s predecessor, entered the test lab at HK’s factory in Oberndorf, Germany. The MP2000 took the concept of modularity and lightweight materials to the next level for a submachine gun. Though only a few were built as prototypes for internal testing, the 9mm MP2000 had all of the features and capabilities of the SMG and SMG II, and more. The 5-pound MP2000 included the bolt lock like that of the HK54A1 and gas relief valve similar in concept to that of the SMG II and was modular allowing the gun to be “built up” by the user for the specific task at hand. After a great deal of extensive testing at HK the MP2000 was also dropped from further consideration as a series production gun though the U.S. Navy did order ten MP2000’s for testing for possible use by their SEAL teams. This purchase order was never filled.

In 1998 HK announced the debut of the new UMP45 submachine gun. It was a distant relative of the MP5 with all the influence from experience, testing, design and production know-how of the prototype guns that appeared before the UMP, including the HK54A1, SMG, SMG II and MP2000. While no longer envisioned as a one-gun-does-everything concept, the new HK Universal Machine Pistol does make use of polymer materials in most components of the weapon, weighs only 4.5 pounds unloaded and is available in the more potent calibers of .45 ACP and .40 S&W.

A family of submachine guns seldom seen by more than just a few fortunate individuals and true operators, today the SMG remains HK’s most successful failure.

Ammunition Guidelines and Special Considerations

1. Avoid using corrosive ammunition. It can permanently harm or damage weapons, suppressors and magazines and makes cleaning more time consuming and urgent.

2. Avoid the use of foreign military surplus, reloaded or remanufactured ammunition in your demonstrations unless you are 100% confident in its quality. The function and performance of the weapons is only as good as the quality of the ammunition fed into them. Use new ammunition from the major ammunition manufacturers for the best and most consistent results. If you are forced to buy ammo locally before the demo or borrow strange, untested ammo, try it before the demo and attendees arrive. Don’t be upended on your big day by strange, unfamiliar ammo!

3. DO NOT use ammunition loaded with lead bullets (unjacketed) in demonstrations. They can cause feeding problems in auto-loading weapons and foul bores adversely effecting accuracy. Small shavings of the lead projectile can peel off during feeding, melt and find their way into unimaginable places (gas systems, sound suppressor baffles and vent holes, even firing pin cavities.)

4. Try and select ammunition that is accurate, reliable and clean burning. It should also have the lowest possible recoil to make it easier for the shooter to fire and control the weapon. Stick with the major manufacturers and in particular their “premium lines” (i.e. Federal’s “Hydra Shok”). At least attempt to utilize this ammunition in your portion of the demo to insure top performance.

5. Keep separate the 9mm weapons from those chambered in calibers 10mm Auto and .40 S&W. Keep 10mm and .40 S&W away from .45 ACP. Separate these ammo types and weapons on the firing line to prevent the smaller rounds from being loaded into the larger bore causing potentially dangerous bore obstructions.

6. Avoid using 12 gauge 1 1/8 ounce, 2 3/4 dram equiv., # 9 or 7 1/2 “Light” shells or lighter in the auto-loading shotguns. While in many cases they will function the weapon reliably, some brands do not provide sufficient impulse to reliably operate the mechanism of the weapon in the hands of all shooters. Stick with at least the # 9 “Heavy” loads or defense ammunition (OO Buck, 1-ounce slugs, etc.) for your demo purposes.

7. DO NOT use ammunition in caliber 9mm with a bullet weight of less than 100 grains. Many caliber 9mm weapons, especially those originating from Europe, are designed to function reliably with ammunition loaded to 9mm Parabellum, 9mm Luger or 9X19mm NATO specifications with projectiles weighing @ 124 grains. 9mm demo ammunition should always be loaded with projectiles with weights in excess of 100 grains, preferably in the range from 115 to 158 grains, unless it is tried and proven specialty ammunition (i.e. frangible, blank, etc.) designed specifically to function in the weapon(s) you are demonstrating.

8. Good old “brass” material is still considered by most experts as the best material for cartridge cases. It has a proven record of reliability and strength. Beware of ammunition loaded in steel or aluminum cases. If you must or chose to use non-brass cased ammo, test this ammunition extensively first in your demo guns before your scheduled demo. The relatively soft or brittle non-brass case material and/or the high internal pressures can cause the cases to expand excessively in the chamber (especially into fluted chambers) or actually rupture resulting in poor extraction and ejection and even damage to the weapon or injury to the shooter or bystanders. Beware of the really good (cheap) deals. They are often not always the best choice for an important demo. Remember that many stoppages and malfunctions in otherwise reliable weapons occur as a result of operator misuse, poor maintenance, bad feed devices (magazines, drums and belts) and faulty ammunition.

Avoid using these types of non-brass cased ammunition in your demos unless it is an expressed requirement of the customer. If this is the case, test fire the weapons (two magazines at least) with this ammunition prior to your demo to insure reliable function and use ammunition from the same lot in your demo.

Example 18:

As a result of a successful demo, a local P.D. purchases a brand new sound suppressed 9mm submachine gun with all of the whistles and bells, an investment for a small agency of almost $1,800. On their very first trip to the range with the new expensive weapon they loaded cheap, locally reloaded ammunition into the “silenced” weapon. With each pull of the trigger the shooter and bystanders were absolutely amazed at just how quiet the weapon was, just like in the movies, and almost no felt recoil to speak of. This gun was definitely worth the money! But the ammunition sure wasn’t. After firing 9 or ten rounds in semi-auto the weapon stopped firing. At the same moment an onlooker noted that the target had not been hit once even though it was only 15 yards away. Upon inspection of the weapon it was found that the 10th round did not fully feed or lock into the chamber of the buzz gun. An obstruction caused by 9 projectiles lined up in the bore of the brand new $1,800 weapon kept the 10th round from chambering. For the cost savings of a box of ball ammunition the P.D. bought a new barrel for the new weapon and a great deal of embarrassment.

Lesson: Don’t cut corners on ammo quality.

9. Magazines of assorted ammunition, loaded prior to the actual firing by one of the attendees, illustrates quite well the reliable function of the products with all types of ammunition. Depending on your product this is very effective, as many competing guns are not totally reliable with all ammo types, especially the large cavity hollow points. However, make certain that you trust each type of ammunition that you mix in the magazine and try this as part of your test fire procedure. You can mark the magazine to denote it as a magazine containing assorted ammunition. Better yet, have it in a clear plastic page and ask an attendee to note the mixed ammo types inside and load it at random in the magazine for you. You should shoot this magazine, as the assorted recoil characteristics of varying ammo types may feel strange to the novice who may attribute it to the weapon.

10. Use tracer ammo (or Hornady’s “Vector” ammo) whenever possible in your demo as the visual effect and results of your proficiency downrange are immediately apparent to the attendees, especially when shooting firing briefcases or at non-reactive or long-range targets. However, just keep in mind that tracer ammo is generally somewhat less accurate for precision long-range fire and it is immediately apparent when using tracer ammo when you don’t hit your targets! As tracer is relatively expensive and often hard to get, use it primarily for your shooting and not that of the attendees. Remember to ask permission first before shooting tracer as many ranges prohibit its use or there may be restrictions due to weather conditions. Always have a fire extinguisher handy during the demo and clean the weapons thoroughly as soon after firing to negate the adverse corrosive effects of some types of tracer ammo.

11. Blank ammo – Rarely will you demo guns with blank ammo. But when it might help sell the product keep in mind that generally speaking blank firing is actually harder on most guns than is normal “ball” ammunition. The reason is that a blank round normally does not contain a projectile that gets launched from the bore. This means there is no bullet to act as a gas seal in the bore so additional gas pressure is required to cycle the blank firing gun. This additional gas pressure can cause overfunction stoppages, higher cyclic rates and felt recoil, increased fouling and premature breakage of internal parts.

The roller-locked HK’s (MP5’s, HK33, G3, HK21, etc.) only function reliably with the black tip Dynamit Nobel Plastic Maneuver blank ammunition. This special type of ammunition was more or less created for the roller-locked guns that require additional recoil impulse to reliably work the bolt. The roller-locked HK’s will not function with U.S. M14 or M16 blank ammo (too under powered). The newer gas-operated HK’s (G36, SL8-1) will function with M16-style blank ammo. All require the applicable HK BFA when firing blanks.

If you shoot blanks make absolutely sure you personally control the ammo and blank firing gun. At all costs do not allow the weapon with the BFA attached near live ball ammunition. Mr. Murphy likes this trick where live rounds are inadvertently loaded in with blank ammo. Firing a live ball round into a blank firing adapter can be quite a shock and potential serious hazard (meaning injury or death!) to the weapon, shooter and bystanders. Though there are new “safety” blank firing adapters (for the HK G36) designed that can “catch” at least one live projectile accidentally fired with the BFA in place this scenario should be avoided at all costs for obvious reasons!

Weapon Specific Guidelines and Special Considerations

1 HK MP5 Family

a. Clean the HK MP5SD barrel and barrel ports using the special barrel cleaning device (ID# 225376) every 200 – 300 rounds during the course of your demonstration. This will help prevent blockage of the gas vents and the annoying difficulty of trying to remove the sound suppressor over an extremely fouled barrel due to lack of regular cleaning.

b. Make certain sound suppressors stay tight and properly indexed for accuracy on all suppressed MP5’s during demo’s to include the MP5SD (this also includes the sound suppressed pistols like the MK23/Mark 23’s and USP45 Tacticals). Poor accuracy, change in the point of impact and even damage to the “can” can result if the suppressor comes loose during your demo. This is where the pot holder or heat resistant glove comes in very handy.

c. Make certain the muzzle and sound suppressor threads are clean and lubed on any “Navy” model MP5’s, to include the MP5/10 and MP5/40, before installing the sound suppressor. Dirty threads may make it difficult to install or remove the suppressor.

d. Use the protective cap for the muzzle threads (where applicable) any time and immediately after the sound suppressor is detached from the weapon. When the sound suppressor is attached to the weapon, the HK MP5 for example, store the protective cap on the thread cap holder (ID# 205483) that fits in the pistol grip of the weapon. This will prevent the threads from being damaged which will prohibit the attachment of the suppressor.

e. To show the consistent tolerances that the MP5 parts are produced to and to demo the ease of repair (simple parts replacement, no fitting required) interchange assembly groups between like weapons. For instance, disassemble various models of MP5’s and interchange their assemblies to create various MP5’s.

Beware however, that not all of the assembly groups are interchangeable. Trigger groups and bolt groups between MP5K’s and those of full size 9mm MP5’s, the MP5/40 & MP5/10 and rifle caliber HK’s many times may fit but in fact are not interchangeable. Bolt locking pieces in K’s, SD’s and A2/A3’s are different, so the bolt groups are not interchangeable though they will fit. Once interchanged, shoot the weapons in the demo with the interchanged parts and change each weapon around again.

f. Use the stronger gray G3/HK91/HK33/HK93 assault rifle extractor springs (ID# 200445) in all of your 9mm MP5’s for increased reliability and durability. Use the unique bent gray-color MP5/10 and MP5/40 extractor spring only in the MP5/10 and MP5/40. The gray assault rifle extractor spring is produced from thicker, stronger wire than that normally used in the 9mm MP5. Install the new spring and try the gun before your demo. (Note: The reason HK still assembles 9mm MP5’s with the copper-colored spring is for some types of ammo that are under powered. With this ammo the stronger gray spring may not allow the extractor to snap over the rim of the case during feeding and locking. The author has never experienced this. In fact the German HK demonstrators use only the gray extractor springs and without problems of any sort.)

g. If the extractor of the roller-locked HK rifles and smgs that use the flat style gray or copper-colored extractor springs (G3, MP5, HK33, etc.) can be easily moved in the bolt head using just one finger, replace the extractor spring! Most often this spring is damaged because people remove it to clean under the extractor. This is not necessary. It can also be damaged and thus needs replacement if there is a feeding or failure to eject stoppage where the round or case pushes out on the extractor as the bolt slams shut bending the spring and making it unserviceable. If the extractor is loose in the bolt head because the spring is damaged the empty case may slip off of the bolt head during the ejection stage and not clear the ejection port. When in doubt, change the spring and don’t leave home without them! This rule of thumb applies to all HK weapons that utilize this style of extractor spring.

Beware if you have a failure-to-feed or eject as the resulting obstruction (live round or empty case) may push outward on the extractor destroying the function of the extractor spring resulting in numerous failure-to-eject stoppages until a new extractor spring is installed. Check the spring and extractor with the finger.

h. If the lips of your 9mm MP5 magazines are bent or the seam in the front of the magazine housing above the oval plate is split and pushed outward at the very top from long term use or abuse, replace that magazine housing or the complete magazine. This split can result in feeding and ejection stoppages.

i. To demo the effectiveness of the sound suppressors on the MP5, shoot the weapons side by side, one suppressed and one unsuppressed and don’t shoot on steel targets or into an indoor range backstop to avoid the excessive noise of projectile impact.

Demo the difference between subsonic and supersonic ammunition in a “Navy” model MP5 by firing a mixed magazine (every three or five rounds) of both through one weapon with suppressor attached.

Don’t forget to add 5 cc’s of water to the wet technology sound suppressors (MP5, USP45T, UMP and MK/Mark 23) for maximum sound reduction. It lasts about 20 rounds or 24 hours without use.

j. Don’t shoot HI impulse ammo in the MP5/10 or MP5/40 fitted with a LO impulse locking piece or damage will occur to the buttstock buffer and or receiver. Generally, you can shoot LO impulse ammo in the weapon fitted with a HI impulse locking piece, and thus shoot mixed or alternating mags of HI and LO impulse ammo, without stoppages. As a rule, LO impulse 10mm Auto or .40 S&W ammunition is most loads under 1,100-fps muzzle velocity. HI impulse ammunition being in excess of 1,100 fps.

However, try this trick with your particular demo gun before attempting it in your demo, as some guns are more sensitive with certain ammo than others. For maximum reliability when using just one type of ammo stick with the correct locking piece for the ammunition that you are using!

Recent developments in .40 S&W ammo (hotter) fired in broken-in (more than 1,500 rounds fired to date) MP5/40’s may require the use of the “HI 25” impulse locking piece to prevent overfunction. Watch for the signs of overfunction (buffer damage, bolt carrier strike on buttstock backplate, roller bulges in the receiver buttstock grooves, etc.) and correct it as necessary.

Underfunction (too little function/bolt velocity) is usually seen as anemic recoil or ejection of the spent cases. In worse case scenarios underfunction may cause failures-to-eject or even feed stoppages as the bolt is not moving far or fast enough in the receiver. In this case try the LO impulse locking piece for that specific ammunition.

k. Use the special 80 degree locking piece (ID# 214292) in the MP5K-PDW when shooting it with a folding stock and sound suppressor attached, especially when shooting the heavy (with a bullet weight greater than 140 grains) subsonic ammo. Like the issues with the powerful 10mm Auto and .40 S&W cartridges the MP5K outfitted as described above can overfunction and run too fast causing failures to feed or eject. Using the 80-degree locking piece will reduce the function of the gun (bolt travel and velocity) and improve its reliability. You can shoot the weapon without the sound suppressor or with lighter 115-grain ammo with the 80 degree locking piece installed without the reliability of the weapon suffering. However, if you’re not shooting with a sound suppressor, the standard “16” MP5K or unmarked MP5A2/A3/N/SF locking piece is best.

l. If you are shooting the MP5K in the HK discreet firing briefcase you must use a standard MP5K with 4.5-inch barrel and “SEF” trigger group. The design of the briefcase prohibits using the longer barreled (5.5-inch) MP5K-N or any MP5K fitted with any of the ambidextrous trigger groups.

m. Review the “MP5 Submachine Gun Family Operators Manual”, available from HK Inc., to supplement your knowledge of the MP5 variants before conducting your demo.

n. Review Part III of this four part series entitled “Specific Safety Guidelines and Precautions” for additional safety related issues that apply to the MP5 that are not listed in duplicate within this section.

o. Don’t mix 9mm and 10mm/.40 S&W flash hiders on 9mm MP5’s and 10mm/.40 S&W MP5’s and make certain that the locking lever on the flash hider (and MP5 BFA) is properly engaged and locked closed before firing the weapon or you risk launching it down range. At a minimum your accuracy will suffer if projectiles strike the improperly attached flash hider.

2. USP Pistols

a. Use the correct magazine in the right USP! The 9mm and .40 S&W magazines look almost identical to one another, except for the markings on the magazine body. The mags are interchangeable but 9mm rounds do not feed reliably from the .40 S&W magazines and stoppages may occur. Mark or constantly check these magazines during demos.

b. As with all self-loading pistol designs, maintain a firm grip on the USP to insure reliable function. Don’t “limp wrist” the USP, especially the .45 caliber models.

c. Keep the sound suppressors tight on those USP’s (and MK23/Mark23’s) that provide a means to mount such devices. Such suppressors from Knight’s Armament Company use internal rubber O-rings to hold the suppressor tight and secure on the barrel during transport and firing. Make certain these O-rings are present (they blow off easily when using compressed air during cleaning) before your demo and carry a spare or two in your parts kit.

3. MK/Mark23’s and USP45 Tacticals

a. While they look alike, the magazines for the MK/Mark 23 and USP45 are not the same. The MK/Mark 23 magazine floor plate is contoured with the opening to the magazine well. The floor plate of the USP45 is not. They should not be mixed as reliability can be adversely affected.

b. MK/Mark 23’s are most impressive when shot at ranges of 50 to 100 meters and are very capable in proficient hands at longer distances to show their superior accuracy, with and without the sound suppressor attached.

c. Use only HK-approved sound suppressors on these pistols. It takes a great deal more than threading the barrel of a short recoil-operated handgun to insure proper function and system reliability. If the sound suppressor is not properly designed for and timed for use on a specific model pistol the weapon can be permanently damaged in as few as 20 rounds fired. When properly tuned for the pistol the sound suppressor will have little or no ill effect on the function or durability of the host handgun. At the time of writing, the Knight’s Armament Company and Bruegger & Thomet sound suppressors are approved for use on the HK pistols after extensive testing by HK.

d. If using wet technology sound suppressors such as the fine KAC version for the MK/Mark23 and USP45 Tactical, do not miss the opportunity during your demo to fire the combo “wet” by adding the prerequisite 5 cc’s of water. The difference to the human ear is dramatic.

2. Roller-Locked HK Rifles (G3, HK33, HK53, HK91, HK93, PSG1, etc.)

a. If shooting blank ammunition, insure the blanks are the black serrated tip “Plastic Maneuver” blanks available from Dynamit Nobel in Cloister, NJ. Only these special blanks designed specifically to operate the roller-locked actions of the HK rifles (and MP5’s) will reliably function the weapon with the HK blank firing adapter. Conventional US blanks designed for gas-operated weapons do not provide the required recoil energy to properly actuate the roller-locked breech of the G3 rifle and its many descendents.

b. Beware of after market scope mounts that clamp to the receiver of the rifle using screws or rotary locking knobs. The degree of torque and the extent that these mounts can be tightened is generally not limited by design. It is thus possible with such mounts to over tighten the mount to a point where the free movement of the bolt group is impaired during firing leading to improper function.

c. Trigger groups and internal trigger mechanisms for 5.56mm, 7.62mm and even pistol caliber HK roller-locked weapons look very similar and can be accidentally and unknowingly interchanged. Generally the ejectors for different caliber HK roller-locked guns are different and thus these parts should not be swapped between weapons. It is very easy to install an MP5 trigger group in an HK53. The ejectors are different so the function of the weapon will be adversely affected. If you are unsure, consider marking or color-coding the trigger groups and mechanisms to prevent this simple mistake.

d. Buffers. There have been many changes in the 5.56mm HK rifle buffers over the past 30+ years. The general rule of thumb is the 5.56mm HK roller-locked rifle should have at least one buffer, two is generally not a bad thing but should also be avoided. Early HK33’s, HK33K’s, HK53’s and HK93’s and their variants had a strong spring buffer incorporated into the back end of the bolt carrier. At some point during the production of the weapon the buffer was moved from the bolt carrier into the back plate of the buttstock. Ensure your rifle has a spring bolt buffer in either location and do not use MP5 buttstocks (fixed or retractable) in the 5.56mm HK rifle for any reason. The buffer prevents what can become extensive damage to the tail end of the rifle’s receiver if the bolt begins to strike the backplate of the buttstock. (When functioning in its optimum range the bolt should stop just short of hitting the buffer or buttstock, though this can easily change depending on the ammo used, the age of the weapon or the bolt gap in the bolt group).

e. Do not exchange bolt heads or bolt groups in HK-roller-locked rifles, especially those that are well used without first checking the bolt gap. The gap between the rear side of the bolt head and front side of the bolt carrier when measured up through the magazine well, with the weapon assembled, the bolt forward and the hammer down should be .1 – .5 mm. The rifles prefer a slightly larger bolt gap, say .3 – .5 mm as bolt gap normally decreases (tightens) with use. Too much or too little bolt gap can effect the weapon much in the same way as improper headspace and can cause failures-to-extract, eject, feed and lock. Bolt gap should be checked every 5,000 to 10,000 rounds and adjusted using pairs of larger or smaller rollers as necessary.

5. G36’s

a. Cool early non-heatshield equipped forearms with water, or exchange them during shooting to reduce or eliminate overheating that can make the weapon hard to handle during extensive firing sessions, such as long demos. New forearms for the G36 created for the Spanish Army in 1999 include internal heat shields to reduce the transfer of radiant heat through the forearm to the shooters hand.

b. Check or reconfirm zeros anytime the carrying handle assembly is removed or reinstalled. Tighten the mounting screws using the torque screwdriver available from HK to 250 Ncm to insure consistent return to zero after remounting.

c. For the correct G36 250 meter battlesight zero at 25 meters the POI for all rounds should be 1.75 inches below the POA with red dot and optical sights.

6. HK21E and HK23E Machine Guns

a. Use only pre-linked U.S. M13 link ammo belts (M27 in the HK23E) or new links with good quality ball ammo in the HK21E. HK21E’s imported into the U.S. after 1998 are designed to use only U.S. M13 (German DM6) disintegrating link belts. These newer guns should not be used with German DM1 non-disintegrating link belts. NEVER USE used links if at all possible as damaged links can change the feed pitch of the belt through the ratchet feed system reducing reliability.

b. Use the # 9 locking piece (ID# 222102) in the HK21E and HK11E? fitted with either 17.7 inch or 22.0 inch barrels for optimum belt pull and function.

c. Use a lot of oil, preferably Breakfree CLP on the bolt group (on the locking rollers and the gap between the locking piece and bolt head from below) before and periodically during firing (@ every 1,000 rounds) to insure positive functioning when the bolt gets hot, dry and excessively ladened with carbon fouling. Failures to lock will occur if lube is needed.

d. HK21E buffers take a beating as a result of prolonged hard use. Watch the inside of the stock backplate around the buffer bolt for signs of bolt carrier impact, a sure sign of the need for a new buffer spring or buffer assembly.

e. 1,000 round continuous cyclic bursts in demos are impressive but risky due to the lack of lube and build-up of carbon. 500 round bursts are safer to conduct (less chance of stoppages) and cheaper. Properly maintained HK21E’s will drag a full 1,000 round belt along the ground without assistance during firing, a show of immense belt pull and strong function.

f. Check for the correct position of each round within the link before your demo, especially after the belted ammo is handled or transported. As in most belt-fed machine guns, stoppages will occur if the round is severely out of position within the link. When feeding or dragging a 500 round belt on the ground give it something smooth to slide on (pavement, cardboard, hard ground, etc.) not grass, stones, sand or mud.

f. The HK21E is most impressive when fired for accuracy, though this trait is generally not considered important in a crew-served weapon. The guns are capable of sub-MOA accuracy with and without telescopic sight, a belt-fed sniper rifle if need be. For special operations or special law enforcement applications this trait is very useful for precision engagements, to avoid stray rounds and to insure greater hit percentages on target.

g. The HK21E or HK23E provides the best (tightest) 3-round burst and full auto cone of fire (group size downrange) when held and fired from rigid positions. When firing with the bipod use the old-style bipod with non-adjustable length legs for maximum rigidity. Dig the feet of the bipod into the ground and slide your body up against the dug-in bipod legs for a very stable position. Use the non-firing hand to hold the buttstock up into the shoulder.

In the assault firing (standing) position ALWAYS use the assault grip mounted at 45 degrees to the left for the non-firing hand. Adjusting the sling so that the non-firing arm can just barely be locked out with the sling held rigid over the non-firing shoulder and under the firing arm. This firing position provides stability close to that of the bipod firing position above when an aggressive stance is utilized.

7. Benelli Shotguns

a. Inertia-operated Benellis, such as the M1 and M3 models, work best if not held extremely tight against the shoulder, primarily when shooting light # 9 or 7 1/2 shot ammunition. Give them room to recoil rearward initially so the inertia spring can be compressed by initial recoil. Adding too much weight to the inertia-operated Benelli, such as ammo carriers or heavy sights and mounts, can also adversely affect reliability. These Benelli models definitely have a break-in period of @ 250 rounds before the customary Benelli reliability can be expected from all sample guns.

b. Shooting the pistol grip equipped Benelli one-handed makes quite an impression on attendees and it can be done fairly easily and comfortably to demonstrate the weapon’s reliability even when held in a non-conventional shooting position. Use defense ammo (OO buck) to insure reliable functioning.

c. Make certain the magazine extension and ghost ring sight components stay tight on the weapon during prolonged shooting sessions. A drop or two of blue Loctite thread fastener on the threads will secure these components yet allow them to be easily loosened or removed when necessary.

Closing Comments

There you have it. Suggestions made from experience for those of you who must conduct demonstrations as part of your profession or business. Always keep the KISS principle in mind as Mr. Murphy loves to come to demos if invited. Keep him away through thorough preparation and attention to detail. When in doubt, leave it out (of the demo).