Interdynamic AB KG-9 Review

The Interdynamic AB KG-9 is the 1980's open-bolt father of the TEC-9 “assault pistol."

July 30, 2020 By Will Dabbs, MD

The year was 1981, and the country still reeled from double-digit inflation spawned by a catastrophic Jimmy Carter presidency. The U.S. and the USSR stared intently at each other from atop tens of thousands of nuclear weapons. Persistent fallout from the Age of Aquarius, our failed foray in Vietnam, and the recent oil crisis shaped current events. Pulling out of the seventies; the hair was big, the people were weird, and fashion trends could foment blindness if gazed upon unduly.

Interdynamic-KG-9-Review — The KG-9 pistol triggered a tsunami of large-framed pistol-caliber firearms in America. Here we see George Kellgren, the designer of the KG-9, with coworkers back in the early days. (Photo courtesy George Kellgren)

The Russians were trying their hand at subduing Afghanistan, and newly minted Middle Eastern terrorists began queuing up for their AK rifles and suicide vests. The Iranians had recently held our hostages for more than a year, and Mount St. Helens reminded everybody that volcanoes were still a real thing. The cumulative result was a veritable cornucopia of fear, uncertainty, and fervent preparation for the pending end of the world.

The American gun culture as we know it was in its infancy, and our burgeoning obsession with survivalism was just finding its legs after the term “civil defense” began to fade away. Al Gore had not yet invented the Internet, and there weren’t near as many black gun enthusiasts in circulation back then as there were “Elmer Fudds.” Then somebody realized we really never were more than half an hour away from nuclear annihilation, and the market for social guns with end-of-the-world applications veritably exploded.

There were many “assault” gun models to choose from in the early 1980s: Valmet M62s, M76s, and M78s, Thompson semi-auto “gangster guns,” AR-180s, FALs, HK93s, HK91s, Mini-14s, M1As, SIG AMTs, M1 Carbines galore, and some others. The most commonly-desired model was the AR-15 SP1. The Bushmaster Arm Pistol was delightfully strange, while Gordon Ingram’s MAC guns were slowly gaining a toehold, in open-bolt form. Wilkinson Arms made the Linda pistol after the intro of their Terry carbine, and the Enforcer handgun version of the M1 Carbine both looked cool and hit hard. Into this shallow pool (when compared to vast number of hunting-style firearms) splashed an inexpensive little smoke pole from Sweden that ultimately induced the vapors in many of the less durable members of society.

The Swedish semi-auto KG-9 originally began as a compact economical military machine pistol. This tidy little buzzgun was built around a simple drawn steel tube and featured a sliding wire stock and angled forward handgrip. The gun was selective fire and ran from the open-bolt. The design was based loosely upon the Swedish K/Carl Gustav M45 that armed American Special Forces advisors in the early parts of the war in Vietnam. The company called this revolutionary little assassin’s weapon the MP-9. The trouble was that nobody anywhere wanted it. Production ceased at less than twenty-five copies.

In many ways, the full auto MP-9 suffered from the same disease that afflicted the MAC-series guns that were its prime competitors. These guns were so small that there remained little room for bolt travel. Abbreviated bolt travel equaled astronomical rates of fire. Astronomical rates of fire made these full auto guns nigh uncontrollable in semi-skilled hands.

Faced with a dearth of interest by the world’s mainstream militaries, Interdynamic AB tweaked the design a little bit, and I do mean a very little bit, and released the gun into the American civilian market as a semiauto open-bolt pistol. The sleeping giant that was America’s gun culture was just beginning to stir, and Interdynamic AB was poised to ride the crest of the wave.

The open-bolt semiautomatic KG-9 was the very image of simplicity. The receiver was a steel tube festooned with ventilation holes, the bolt weighed about a pound, and the firing pin was nothing more than a little nubbin machined into the bolt face. The fire controls rode in an inexpensive polymer housing, and the gun fed from a detachable 32-round box magazine patterned after that of the Swedish K. The sights were steel and rigid, while the sling attachment points were welded onto the left aspect of the receiver tube. The magazine release was a simple midline lever located AK-fashion behind the magazine. The sole safety consisted of a bolt-locking slot like that of the Sten gun.

Around 2,500 of these open-bolt semiauto guns rolled off the lines before the BATF declared the design to be so readily convertible to full auto as to be “unsafe” in the hands of mere civilians. You really could convert these guns to rock and roll in about ninety seconds with a Dremel tool. Open-bolt KG-9 pistols, along with all open bolt semi-auto firearms, produced after January 19, 1982, were arbitrarily declared machineguns subject to the onerous $200 tax and registration requirements. However, all open-bolt semi-autos made before this date are grandfathered, unless the firearms could shoot full-auto without modification.

As this ruling fell before the May 19, 1986, cutoff for manufacturing machineguns for civilian consumption, many of those original 2,500 open-bolt KG-9’s found their way into the NFA registry as legally-registered sputterguns. Those remaining open-bolt semiauto versions, made before the 1982 deadline, appreciated in value at a rate far out of proportion to their intrinsic worth. I’m embarrassed to admit what my copy set me back when I tripped over it on a recent online auction.

The original Interdynamic AB KG-9 was the brainchild of two men. The first was a Swede named George Kellgren. The second was a Cuban-American gun designer named Carlos Garcia. The KG part of KG-9 takes it inspiration from the last names of these two men.

Kellgren parted ways with the Interdynamic AB Company in fairly short order, but he has remained quite busy since then. You will recognize his work in his subsequent company Kel-Tec (KelTecWeapons.com). If you step back and look at the KG-9 alongside more modern Kel-Tec products like the RFB, KSG, SUB-2000, and PMR-30 the evolutionary family resemblance becomes obvious.

Mr. Garcia tended the company tiller through some fairly sordid stuff after Kellgren’s departure. The BATF reclassification of the KG-9 into a “semi-automatic machinegun,” whatever that really is, forced a tweak to the design. By contriving a bolt with a floating firing pin, and adjusting the geometry of the sear mechanism the exact same chassis, it became the closed bolt KG-99, with the exception of the addition of a steel plate to engrave the serial number (the government frowns upon people melting away serial numbers with hot butter knives). The BATF was, for the time being at least, placated. Sales remained brisk.

In 1984 Interdynamic AB became Intratec, and the gun was renamed the TEC-9. Aside from one major upgrade and a few esoteric adjustments to the sights and charging handle it was the same gun. The biggest improvement was in the back of the receiver. Those early guns absorbed all their recoil energy into the polymer frame. The use of hot 9mm would eventually crack the polymer and render the gun useless. Starting with the TEC-9 the rear of the receiver was threaded and a steel plug introduced that made the guns essentially indestructible.

The TEC-9 looked scary, so it found its way into a recurring role on shows like Miami Vice, usually toted by well-dressed drug dealers. The gun showed up on the big screen movies like Kurt Russell’s Big Trouble in Little China and in countless other movies and TV shows.

Trigger Time

I ran the KG-9 alongside a 9mm Glock 17 equipped with a 33-round magazine. The Glock was more comfortable, more concealable, and more accurate. The open-bolt nature of the design substantively degrades accuracy, and the pressed steel sights don’t make that any better.

However, at reasonable ranges the KG-9 will indeed group fairly well and look cool doing it. My copy shoots about a foot low at fifteen meters. The open-bolt design is quite the novelty this deep into the Information Age, and it is a reliable conversation-starter at the range. I’ll never shoot mine enough to wear it out, but the potential failure of the polymer lower would be a concern had I designs on using the thing for any serious stuff.

Philosophy

I’ve never fired a full auto Swedish MP-9, but I have logged more than my share of trigger time on its American cousin, the 9mm MAC-10. That gun is small, heavy, and ridiculously fast. As a result, it loses its allure after a couple of magazines. Were I to be chased by a maniacal drug dealer I would sooner he be armed with a converted full auto KG-9 than a pump shotgun or a typical bolt-action hunting rifle. However, truth be known, I would sooner not be chased by a maniacal drug dealer at all.

The KG-9 ultimately fell prey to the prejudices of the uninitiated. The gun is admittedly easy to convert to full auto, but anyone who has logged any serious time on automatic weapons will attest that full-auto fire is grossly overrated in anything other than belt-fed guns. Movies make machineguns of any stripe seem fairly devastating, but I have it on reliable authority that movies are not actually real.

Denouement

The KG-9 was a fascinating speed bump in the history of modern American firearms. Though it was produced for less than a year and really saw very little practical usage, its influence on the subsequent evolution of the gun culture was far out of proportion to its actual effectiveness. The open-bolt KG-9 was produced on such a small scale as to have been little more than a footnote. However, there were roughly a quarter million of the subsequent closed-bolt guns produced, and they did indeed make a splash.

The legacy of that first KG-9 was both convoluted and lengthy. The KG-9 begat the KG-99 that begat the TEC-9 that begat the TEC DC-9 that begat the TEC DC-9M that begat the AB-10. DC means “Designed for California” after their first “assault weapons” ban. AB stands for “After Ban” in reference to the 1994 federal “Assault Weapons” Ban. It really was not unlike a legislative versus engineering Whack-a-Mole game. Subsequent knockoff designs were too extensive to be readily catalogued. When the dust settled the gun grabbers got the KG-9, but we kept the AR15. I think we came out on the better end of that deal.