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I operate under the belief common knowledge is necessary for the citizens of a constitutional republic.  When they’re uninformed on any given topic of importance, bad laws are written and bad things happen to good people.  When they’re purposely misinformed, things can be even worse.  One of the topics on which most Americans are uninformed, and surely misinformed, is automatic weapons.  This primer may help.

Gen. Hertling, doing it wrong…

In CNN: Not Here To Pump Up Liberty, I wrote of CNN reporter Gary Tuchman, coached in shooting a fearsome AR-15 by a retired Army General.  Not only did both demonstrate poor firearms skills–-actually dangerous gun handling–-the General spoke of the AR-15 featured in CNN’s video as a “full semi automatic.” The General may not have been trying to trick people into thinking the most common, popular semiautomatic rifle in America is a machinegun–he later claimed he was not–but that is a time-tested gun control tactic, one very much in use circa May, 2022.

Upon occasion, gun banners have accidently revealed their real intentions, as Josh Sugarmann did in 1988: 

The public’s confusion over fully-automatic machine guns versus semi-automatic assault weapons — anything that looks like a machine gun is presumed to be a machine gun — can only increase the chance of public support for restrictions on these weapons.

 As regular readers know, fake Hispanic Beto O’Rourke, in his latest attempt to be Governor of Texas, at first tried to claim he wasn’t after everyone’s guns, but quickly reversed course and reverted to his true, anti-liberty/gun views.  Temporary President Biden swore he would make O’Rourke his “Gun Czar,” but that has not come to pass.  Perhaps even Biden is sufficiently mentally alert to know what a loser O’Rourke is, or at least Biden’s handlers are.

The August, 2019 El Paso attack, carried out with an AR-15 variant, has demonstrated yet again how little most Americans know about submachine guns, and their rifle caliber cousins: semiautomatic rifles that outwardly resemble actual assault rifles.  Rifles of all action types and descriptions are used in only a tiny portion of all shootings, and AR-15-like rifles, in a tiny portion of that tiny portion. The purpose of this article is to provide a submachine gun primer, with some clarifying mention of their larger, rifle caliber, brethren.

Until 1934, Americans could own machineguns without restriction.  It was Prohibition, and the organized crime it birthed, that made criminal machinegun use newsworthy, and the 1934 National Firearms Act, enacted a year after the repeal of Prohibition by the 21st Amendment, regulated possession, imposing a $200 non-transferrable tax, government registration, background checks (fingerprinting, photographs, etc.) and storage requirements, all of which take many months–-sometimes more than a year–to process. The same process is currently required for suppressors.  During the Trump Administration, there was some Republican talk about removing suppressors from this onerous and unnecessary process, but somehow, Republican “leaders” just never got around to it.  Despite having complete control of Congress and the White House for some time, congressional “leaders” never felt “the time was right.”  Mitch Mc Connell remains in a position of power in the Senate where this issue never seem to see the right time.

The Gun Control Act of 1968 froze the importation of any new automatic firearms for citizens, and in 1986, the Firearm Owners Protection Act was passed, primarily to end rampant government abuses of law-abiding gun owners. During final debate, late at night when most of the Representatives were gone, a Democrat introduced an amendment, and the execrable Charles Rangel (D-NY), the presiding officer at the moment, called for a voice vote. Even though it was obviously defeated, Rangel declared it passed.  As usual, Republicans rolled over and hoped no one would say mean things about them–-D/S/Cs had not yet hit on reflexively calling everyone and everything “racist”–-and all fully automatic firearms manufactured after May 19, 1986 became unavailable for citizen ownership (18 USC 921).  D/S/Cs have so successfully demonized common semiautomatic rifles, that provision has never been struck down.  One can still own a fully automatic gun, following the procedure established in 1934, but the 1986 amendment essentially froze the number of such weapons in circulation. It’s still possible to own a machinegun, but it must be a weapon manufactured prior to 1986.  It’s a seller’s market, which means automatics are rare and very expensive.

Before we go further, let’s clearly define the weapons we’ll be considering:

Smith & Wesson M&P 15, a common AR-15 variant

Semiautomatic Rifles: A semiautomatic firearm, regardless of outward appearance, fires one bullet for each pull of the trigger. This technology was invented in the late 1800s. The AR-15 rifles so commonly demonized by the media and anti-liberty cracktivists (I know, I repeat myself) are semiautomatic. Their selector switches have only two positions: “safe” and “fire.”  There is no such thing as an “assault weapon,” despite some Democrats/Socialists/Communists having put that nonsense term in legislation, but a working definition might be: “any gun anti-liberty/gun cracktivists want to ban at the moment.”

Anti-liberty despots avoid mentioning they have already had a federal ban on “assault weapons.” Weapons such as the AR-15, and magazines holding more than 10 rounds, were banned from 1994 to 2004 under the Clinton Administration. When the law sunset, even D/S/Cs had to admit it accomplished nothing for public safety.  It cost D/S/Cs dearly in elections, and most have hesitated to vote for gun control since, though their behind the scenes efforts never flag.  With the 2020 election, that trend has reversed and many D/S/C strategists proclaim gun control a winning issue, though as this article is written, the Constitution remains the winner.  As always, this has not prevented D/S/Cs from pushing a blizzard of anti-liberty bills in the Congress and throughout the nation.  Fortunately, the Supreme Court majority seems to be willing to actually uphold the Constitution—for the moment.

L to R: .22LR, 9mm, .223, .308

M1 Garand Battle Rifle

Battle Rifles: These are shoulder fired, full sized rifles firing a full-power cartridge like the .308 or 30.06. Because they are uncontrollable in full auto fire–-they’re too light and not designed for it–-they are almost always semiautomatic firearms, though one can argue that some early bolt actions rifles were also battle rifles. They are generally larger and much heavier than assault rifles, and their cartridges are large and heavy as well.

Suppressed AR-15
credit: thefederalist

Assault Rifles: These are shoulder fired, magazine fed rifles firing a rifle cartridge of intermediate power. They are not “high powered” rifles. Some assault rifles may outwardly resemble semiautomatic AR-15s, but they are available for citizen ownership only under the legal restrictions already outlined. The military does not use AR-15s, but fully automatic rifles, most commonly designated “M4.”  The only way for most to tell one from the other without disassembly is most automatic rifles have selectors with three positions: “safe,” “fire” and “auto.” Rather than a full auto setting, some are capable only of firing two-three rounds at a time on automatic, a “burst” option intended to enhance accuracy and reduce ammo consumption, always a major logistical issue in combat.

H&K MP5 Submachine Gun

Submachine Guns: These are fully automatic firearms, usually shoulder fired–-non-shoulder fired weapons have limited utility–-which fire pistol cartridges, such as the .380 ACP, 9MM, or .45 ACP. There are, however, semiautomatic versions of some of these weapons that outwardly resemble their fully automatic cousins, except for having at least 16” barrels and at least a 26″ overall length (for rifles and shotguns, though shotguns must have at least 18″ barrels), another federal requirement. Pulling the trigger and holding it back will allow such weapons to continually fire until they overheat, malfunction, or their ammunition is exhausted, in other words: true fully automatic fire. Like assault rifles, their selectors have at least three settings.

Browning M2 Heavy Barrel Heavy Machine Gun, Tripod Mounted

Machineguns: These are much larger and heavier weapons firing full power rifle or machinegun cartridges, such as the .308/7.62 NATO, 30.06 or the .50 Browning Machine Gun, and tend to be crew-served weapons, requiring a gunner, and one or two loaders to feed ammunition on linked belts and to carry them and the gun’s tripod, all of which are large and heavy.  To save ammunition and to avoid overheating, they are usually fired in 3-5 round bursts. Some modern machineguns–such as the M249–are light enough to allow a single soldier to carry and fire them, but this class includes weapons so large and heavy they are commonly vehicle mounted. I’ll mention miniguns, modern, electrically driven versions of the Gatling Gun, which if sufficiently large, can also fire cannon–-explosive–-rounds.

The A-10’s GAU 8/A 30mm cannon and its ammunition bin
credit: defencetalk.com

The A-10 attack jet mounts a huge 30mm rotary cannon.  In fact, the jet was designed around the cannon, requiring its front landing wheel assembly to be offset from the aircraft’s centerline.  Not true machine guns–-their mechanisms are very different–-they are used to fire a great many rounds at fast moving targets, such as aircraft and missiles attacking naval vessels.

M249 SAW

This is the M249 SAW (Squad Automatic Weapon.  It fires the same .5.56mm cartridge as the M-4, but is able to sustain automatic fire for much longer periods of time.  It normally fires from a plastic box magazine containing some 200 linked rounds.  It is much lighter than the Browning and other general-purpose machineguns and is commonly carried by a single soldier.

As to my background to discourse on this subject, regular readers know of my general firearms, military and police background. Those experiences, as well as an interest in firearms have allowed me many opportunities to study, fire, and to dissemble and examine many of the submachine gun designs currently on the market. I’ve a reasonable amount of practical experience with common general purpose (AKA light and medium), and a few heavy machineguns. I also hold an instructor’s certification for submachine gun from the American Small Arms Academy.

Most of what the public thinks it knows about submachine guns from TV and the movies is wrong. Unlike the “shoot from the hip” and “spray and pray” methods Hollywood favors, and unlike the unlimited magazine capacity, full-auto shoot fests often portrayed on the silver screen, submachine guns are most effective when fired from the shoulder, when the sights are used, and when fired in two to three round bursts. There are potential uses for extended fully automatic fire, but they are relatively uncommon, particularly in police work.  Even in the military, that kind of suppressive fire is most commonly done with true machine guns.

Submachine guns may be generally understood to be relatively compact, short barreled (usually 6” to 10”), shoulder fired small arms firing pistol cartridges, and are capable of semi and fully automatic fire. There are various subcategories and variants of this description. Some weapons add burst capability, or substitute it in place of fully automatic capability, and there are even a few fully automatic pistols, such as the Glock 18 and the Beretta 93R.

Beretta 93R
credit: berettaweb.com

The only outward difference between a Glock 17 and Glock 18 is the slide mounted selector switch.  As Glocks have no external safety lever, the selector functions only to select semi and full auto fire.  As long as bursts of 2-3 rounds are employed, the G18 is no less controllable than the semiautomatic only G17.

Glock 18C
credit: powerand technology.blogspot.com

Because they fire pistol cartridges—most commonly the 9mm and .45 ACP—and because they generally have short sight radiuses and short barrels, effective submachine gun range is usually considered to be no more than 100 yards, and optimum employment is at common–-25 yards and less–-pistol ranges. Various red dot or laser sights may be helpful with submachine guns, as they are with many firearms, but most submachine guns, particularly first and second generation models, were not designed to be equipped with this sort of accessory, and require modification–-usually by a gunsmith–-to accept them.

1928 Thompson
credit: rockislandauction

First generation submachine guns employ old-world manufacturing methods and materials. They tend to be time and labor intensive.  Many are beautiful examples of the gun designer’s art, and very rugged and lasting, but also very expensive. Perhaps the best-known first generation submachine gun is the Thompson in its 1928 incarnation, and later, in the WWII era M1 version. Prior to WWII, the 1928 version cost well over $3000 dollars in 2021 equivalent dollars. While the M1 was still too costly at $42.94 each, it was much cheaper than the 1928. It saved money by omitting bluing, an adjustable rear sight, the compensator, the ability to mount drum magazines, an easily detachable butt stock, the finned–for cooling–barrel, and the internal Blish lock, a device that was said to reduce recoil and smooth the action.  Consider this cost compared to that of the M3 “Grease Gun,” also in .45 ACP caliber, at $20.94 each.  

Having owned a model 1928, and fired others, including M1 Thompsons, I’ve never been able to detect any difference in performance or feel between Thompsons equipped with a Blish lock and those without.  Even the much less expensive M1 was still too expensive for an army that needed huge numbers of reliable, quickly manufactured guns.

Thompson M1 submachine gun

Despite what some might consider flaws, the Thompson was prized by combat troops.  It is still in use around the world. Its relatively slow cyclic rate of around 600 RPM is considered ideal by many and makes firing bursts of two and three rounds easy by trigger manipulation alone, which is how professionals fire such weapons.  Even single round fire is, with practice, easily obtainable.  Its .45 ACP cartridge is also unquestionably effective.

Sten Gun
credit: cgtrader

Second generation submachine guns make use of tubing and stamped and welded metal rather than machining, using machined parts such as the bolt only when absolutely necessary. This greatly reduces manufacturing time and costs. Their tolerances are sufficiently loose as to require little or no hand fitting.

S&W M76
credit: modern firearms

Sterling submachine gun

Common examples of second-generation weapons are the British Sten and Sterling (a more sophisticated weapon), the US M3 “Grease gun” and the Smith and Wesson M76. These weapons tend not to be pretty and usually have crude, non-adjustable sights, but they function reliably.

credit: americanrifleman.com

Another feature of second-generation weapons is the suppressor, usually not as an integral part of the design, though some integrated designs were produced. Keep in mind there is no such thing as a “silencer.” Suppressors merely reduce the decibel level of firing to less than hearing damaging levels.  Suppressed gunfire still sounds like gunfire.

credit: enwikipedia.com

Third generation submachine guns continued the trend of second generation weapons in using folded, stamped and welded metal, but added a telescoping bolt that when closed encompass some length of the barrel. This allows a much shorter, lighter and more compact weapon while maintaining a reasonable barrel length, usually in the 10” range. They retain much of the low manufacturing cost and time of second-generation weapons.  Folding and/or retracting stocks also contributed to shorter weapons, but often at the expense of proper stock length. This is not such a problem for people of small stature or those wearing thick tactical vests or body armor. Third generation weapons also make greater use of plastics than previous designs.  Common third generation weapons are typified by the excellent Uzi and its several variants. Designed for a sandy, desert environment, they are unfailingly reliable.  The iconic H&K MP5 combines features of second and third generation guns.  Note the Uzi’s top mounted cocking handle, which makes optical or laser sights inconvenient to attach.  That the top cover–which is not rigidly attached to the frame– is lifted up and off to remove the bolt group for cleaning doesn’t help either, as optical or laser sights need a solid mounting.

Kriss Vector

Is there such a thing as a fourth generation submachine gun?  If so, the Kriss Vector may be the first of the breed, and arguably, something approaching a fifth generation, though it may be too early to declare a specific fourth generation. The Kriss employs several unique design and manufacturing features. Making extensive use of plastics, and employing a unique and effective recoil-reducing mechanism–-thus the odd, boxy appearance of the lower receiver–-the gun’s appearance is unlike any other submachine gun and is also designed to accept now commonly available accessories such as optical sights, lasers and flashlights. Employing the 9mm or .45 ACP cartridges and using readily available Glock magazines, the Kriss might be considered a logical evolution of the Thompson, while fixing its supposed size and weight drawbacks. Note the side-folding stock. The Kriss is far lighter, arguably more ergonomic, much more compact and more adaptable to a variety of missions.  It also features a bore axis below the trigger, which doubtless helps in recoil control.

Kriss Vector CRB

Kriss also makes a semiautomatic version of the Vector, the CRB, which is available in 9mm and .22LR.  Notice the collapsing, AR-15-like stock, and the non-functional suppressor, which encircles the federally mandated 16″ barrel.  Its current MSPR is $1575.00.

Virtually all first, second and third generation submachine guns were not designed to easily accept accessories such as optical sights. When they were originally developed, such things either didn’t exist or were in their developmental infancy. However, various mounts of varying degrees of effectiveness are now available for most popular submachine guns and their semiautomatic versions.

Submachine guns fire from either an open or closed bolt. An open bolt is generally considered necessary for arms intended to be used in combat and subject to sustained automatic fire. If the weapon becomes too hot–-this happens incredibly rapidly under sustained fully automatic fire–-rounds can “cook off,” or detonate merely by contact with the superheated chamber, which can be dangerous indeed if the bolt is not fully closed at the time.

A pull of the trigger of an open bolt action releases a large and heavy bolt to fly forward under heavy spring pressure, stripping a cartridge from the magazine, guiding it into the chamber, and when the bolt is closed and “locked,” firing it. This movement disturbs accuracy, though with correct technique and practice, this problem can be minimized.  A heavy, open bolt may also be accidently released by rough handling, which can be very dangerous indeed, and militaries that employ such arms are very careful about their handling procedures.

The MP5 uses a roller locking system and fires from a closed bolt. While this is, to the way of thinking of many, an overly complex mechanism, it is undeniably effective and tends to enhance accuracy because when the trigger is pulled, there is no heavy bolt flying forward to disturb aim. The MP5 family can overheat if fired on automatic for extended periods, but because these weapons tend to be used in the counter-terror and SWAT roles, extended fully automatic fire is not generally an issue. The good ergonomics, high quality, and accuracy of the MP5 contribute to its continuing popularity.


The purpose of submachine guns–-and machine guns–-particularly in the military context, is to provide a high volume of fire on briefly exposed and/or rapidly moving targets, increasing the probability they’ll be hit. In combat, and in counter terror and police applications, submachine guns are particularly effective at short range, indoors or outdoors. In such situations, it’s important to be able to place multiple rounds of accurate fire on targets to immediately incapacitate them. Properly employed, submachine guns work well.

With few exceptions, submachine guns should be fired from the shoulder, the sights should be used, and trigger control should be accomplished not with mechanical burst regulators, but by the educated and experienced trigger finger of the operator. Movie shooting—firing from the hip, wildly swinging the muzzle with the weapon on full auto, firing one-handed—are guaranteed to empty magazines in seconds and entirely miss one’s target while ventilating the surrounding landscape to no effect, other than damaging property and hitting innocents.

Even a 600 RPM submachine gun will empty a 30 round magazine in about two seconds of fully automatic fire. A 1000 RPM gun will empty a magazine much more quickly. Bursts of two to three rounds manipulated by the trigger finger are easily achieved with proper training and practice. However, with high cyclic rate weapons, this becomes more demanding.

There are many misconceptions about submachine guns. One of the oldest tropes is the muzzle of a Thompson on full-auto will uncontrollably climb up and to the right. Nonsense. A loaded Thompson is an eleven-pound shoulder arm firing a pistol cartridge. While the laws of physics can’t be repealed, with proper technique, the contents of a 30 round magazine can be easily fired on automatic into a paper plate at reasonable engagement distances. The same is true for virtually any submachine gun. A Thompson is not quite as easy to fire this way as an MP5 or a Kriss, for example, but it is certainly not uncontrollable.

Pistol ammunition fired from the longer barrels of submachine guns tends to outperform the same ammunition fired from pistols, achieving higher velocity and greater energy. This, as well as a higher hit probability with multiple rounds at longer ranges, accounts for much of a submachine gun’s effectiveness.

It is not unreasonable to assert that submachine guns are more potentially dangerous than some other firearms. However, all firearms are potentially dangerous, and automobiles are far more dangerous than firearms. As with any firearm, this potential danger can be mitigated by proper training and practice, and since 1934, there is only one potentially confirmed case of a lawfully owned machinegun being used in a crime—it’s actually iffy–-none in a mass shooting. By any reasonable measure, there is no logical or practical justification for restrictive federal regulation.

credit: screencrush.com

Movie shooting is an illusion for dramatic purposes.  Subguns are great fun to shoot, and properly used, are no less safe than any firearm. But submachine guns do have unique qualities that require proper training and careful, focused practice.  Go here for an example of how failing in that resulted in a needless tragedy.

I do not suggest submachine guns are only for the highest-level experts, only that they require professional training and correct practice.  Subguns firing from an open bolt require more care–-more attention to safety–-than those firing from a closed bolt, for example.  As with any gun, one’s full and focused attention must be employed when firing a submachine gun.  That said, as long as one follows the fundamental rules of safe gun handling, any firearm is safe.

And now, gentle readers, you know the truth, and the facts.  Next week, a suppressor—there’s no such thing as a “silencer”–-primer.