Long recognized as one of the world’s great arms designers, Mr. C. Reed Knight, Jr., President of Knight’s Armament Company (KAC), has designed and produced a great variety of firearms, sound suppressors, ammunition and accessories. Many of these products are standard issue with the U.S. military and others.

pdw 6x35mm
The KAC/PDW’s designer, Mr. C. Reed Knight, Jr., demonstrates the weapon during the NDIA Show in New Mexico. There was almost no felt recoil and the gun was extremely controllable.

In the late-1980’s, Mr. Knight entered into a partnership of sorts with his close friend, Eugene Stoner, who designed the renowned 7.62x51mm NATO AR-10 rifle while at the original Armalite Division of Fairchild Company, in Costa Mesa, California. As an aside, although the AR-10 was not adopted (for political reasons) Mr. Stoner never dropped his original idea, and in 1991 designed a variation of it that incorporated some parts commonality with the 5.56x45mm NATO caliber AR-15 (M16) rifle. The result was the Stoner Rifle – 25 (SR- 25), 25 being the sum total of adding 10 and 15.

The SR-25 was such a success that a special version of it was later adopted by the U.S. Navy SEALs as the Mk 11 Sniper Rifle. In 2005 a variation of the Mk 11 was submitted to the U.S. Army’s Semi-Automatic Sniper System Program as the XM110. After exhausting tests, the KAC XM110 candidate was officially adopted as the M110 in early 2006, along with a KAC designed sound suppressor. The entire package including its Hardigg hard carrying case is finished in the Army’s new Flat Dark Earth (FDE) color in order to help defeat enemy thermal imaging devices.

To digress a bit, KAC also designed and produces an entire line of AR- 15/M16 variants in its SR-15 family of rifles and carbines. Amounting to a highly refined AR-15, the SR-15 is specially tailored for top performance and accuracy using the finest materials available. This brief history is intended to bring the reader up to speed not only with KAC’s experience in producing AR-10/M16 style weapons, but also to set the stage for the latest defensive weapon from this innovative company.

The Personal Defense Weapon

For the past 20 years or so there has been an accelerated movement to develop a modern shoulder-fired weapon for close-range defense, a weapon offering easy concealment, good range and great terminal ballistics. Of course such a concept is not new and began a century ago with the stocked pistols and early submachine guns. Many similar contemporary weapons also fire “pistol” cartridges and were designed to fill the same role in mind. In between came the U.S. 30 Carbine, M1 & M2, which fired a cartridge that looked like a pistol round, but performed more like a light rifle cartridge, and had an effective range of 200 meters.

It was this type of performance that inspired the more recent developments, which have spawned the title of Personal Defense Weapon (PDW). Unlike the assault rifle, which was developed to both protect a position from assault and also be capable of assaulting an enemy position, the role of the PDW is to protect against an assault, especially when a VIP is involved.

The problem has been that most of the contemporary PDW’s have either been chambered for a true pistol cartridge, or a small caliber, short, bottlenecked cartridge, such as the 7.63x25mm (.30 Mauser). While resembling a rifle cartridge, the performance of these rounds is relatively limited. Worse is that the weapons that fire them do not seem to have been designed to be held or fired by an average size human being.

(top) The 254mm barrel and 203mm barrel KAC/PDW’s are seen together for comparison. (middle) The 245mm barrel KAC/PDW (below) is seen with the KAC 5.56x45mm M4 style carbine. (bottom) Here the 203mm barrel KAC/PDW is seen with its sound suppressor mounted, compared with the 254mm barrel model above.

One of the main problems of some of these weapons is they are different from what most of the free world’s warriors are used to fighting with. I can sum it up with the terms “ergonomic” and “user friendly.” Most of today’s free-world fighters insist on weapons with controls similar to those of M16/M4 weapons.

Knight’s Armament Company

For the past several years, Mr. Reed Knight has been actively involved in conceiving, designing and developing the “perfect” PDW. The catalyst for this was a growing discontent with the submachine gun, as well as a lack of both mechanical and political support, but especially from a performance standpoint.

With the requirement for a 300- meter accurate and effective range, it was clear that the performance of the 9x19mm cartridge was nowhere close to meeting it. In addition, the SMG weighed about seven pounds, and the maximum weight of a new PDW was set at 4.5 pounds. The SMG was finally on its way out. While a number of new PDW rounds were tested, they could not perform to the 300m threshold in which operators commonly live, fight and die.

At the 2006 SHOT Show in Las Vegas, Nevada, Reed Knight took me aside to show me a new weapon he had developed, but not before he swore me to secrecy. The gun he showed me was an extensively tested prototype of his new KAC/PDW.

A descendant of one of the designs Reed Knight submitted to the Special Operations Forces Combat Assault Rifle (SCAR or SOFCAR) Program, the KAC/PDW bears a remarkable resemblance to the M4A1 Carbine, and is, to a large extent, a miniature of that weapon. With a standard barrel length of 10-inches (8-inches optional), the KAC/PDW has an overall length of just 19.5 inches with its folding stock folded and 28 inches with it extended. The unloaded weight of the 10-inch barrel model is 4.5 pounds.

Some of the reasons for the KAC/ PDW’s ultra-light weight are its specially machine-lightened barrel, its skeletonized buttstock and its bolt group. Unlike the bolt group of the M4, that of the PDW is kin to the Kalashnikov. In the KAC/PDW the AK style bolt group is semi-captive in its own sub-unit framework, and comes out of the upper receiver assembled as such with its own recoil spring. The bolt group is lighter than that of the M4, but this is one of the elements of the KAC/PDW I was not allowed to photograph.

One thing I was (with some hesitation) allowed to photograph was the special logo of the U.S. Government entity for whom the KAC/PDW was developed, the new Technical Support Working Group.

Unique Muzzle Brake

On its unique combination muzzle brake/ flash hider either of the KAC/PDW’s barrels will accept a KAC sound suppressor. This flash hider is one of the secrets of the PDW’s high degree of controllability and it reminds me of the device designed by Gene Stoner on the early AR-10 prototypes, and later on his FARC-3 rifle. This early somewhat complex device appears to have been patterned after the muzzle brake on the WW II German FG-42 rifle, but on the KAC/PDW it is quite simple in operation if not in manufacture.

With a restricted front end this muzzle brake acts as a baffle to halt forward moving high velocity gasses behind the bullet. This gas then pushes forward against the baffle to dampen felt recoil, with the gasses then vented out through one hundred or so tiny exhaust holes in the sides and top of the brake. In addition to further controlling muzzle flip, these holes break up muzzle flash.

Dual Short-Stroke Gas Pistons

Operating the PDW’s bolt carrier are dual short-stroke gas pistons, each with its own spring, which are activated from dual gas cylinders off each side of the gas block/front sight base. I was not allowed to photograph these either, but all recoil and piston springs are housed inside of the gun. With the exception of the right-sidefolding stock, all other aspects of the KAC/PDW are pretty much true to M4/M16 configuration. However, because of the AK-style bolt group and role the KAC/PDW was designed to fill, there is no ejection port cover on the upper receiver.

Also interesting is the arrangement and number of the cross pins in the KAC/PDW’s fire control group. There are three, one for the hammer and one for the trigger, as in the M16, but in the PDW there is an additional pin for the auto sear, and this arrangement appears to be similar to that of the FN-FAL, due to the PDW’s very short bolt carrier. The pins also have heads and enter from the left side of the receiver. A steel retainer on the right side of the receiver holds the pins in place.

When folded, the stock is secured by a steel stud implanted in the right side of the lower receiver.

There is some small parts commonality with the M4 and the receiver sections are made of 7075T6 aircraft grade alloy. The KAC/PDW has ambidextrous QD sling mounts front and rear as well as three locations for a single point sling, such as those offered by Wilderness Tactical, Boonie Packer, Sling Systems, Blackhawk and others.

Other Tactical Additions

Coming standard with an M1913 MilStd flattop upper receiver, the KAC/PDW has a monolithic rail handguard system and uses KAC’s flip-up BUIS. On the top rail can be mounted any optical system including the Aimpoint Comp, Eotech and Trijicon that are already in the system. The side rails will accommodate KAC handguard panels, lights and lasers, and the bottom rail will mount the KAC vertical foregrip. However, on the bottom rail I would opt for the GPS GripPod, which instantly becomes a robust bipod while adding only 7 ounces to the gun.

Also in development by GPS is an offset M1913 mount that will mount its own lightweight polymer M1913 rail at either 5 o’clock or 7 o’clock. This rail will place a push-button end cap light in the ideal location for the thumb of either support hand and do away with wires and all the problems they bring to a mission. One of the best of these lights is SureFire’s new lightweight Scout Light.

To keep the PDW able to be easily stowed in the smallest of places, the M16A2 pistol grip has been highly modified by thinning and shortening its length. However, the weapon will also accept any aftermarket pistolgrip such as those from ERGO, Magpull, TangoDown and others.

Instead of being fluted, the barrel’s exterior is machined with alternating depressions in a patented process developed by KAC. The result is a barrel that is at least as strong as fluting, and with the same cooling features and weight reduction. However, there is yet another reason for the KMC/PDW being lighter than the M4.

6x35mm PDW

Designed entirely around a brand new short .243 caliber cartridge made by Hornady exclusively for KAC, the receiver/magazine-well section of the KAC/PDW is 1/3-inch shorter than those elements of the M4 and that includes the magazine. This because the overall length (OAL) of the KAC/ PDW 6x35mm cartridge is .32-inch shorter than that of the 5.56x45mm NATO cartridge.

The 6mm Hornady bullet fired by the KAC/PDW is of the open tip match (OTM) type and weighs 65 grains. This bullet is loaded in front of a proprietary propellant that was designed especially for the cartridge by Mr. David Emary, Chief Ballistician for Hornady Mfg. The 6x35mm PDW cartridge is based on a modified .221 Fireball case, which itself is a shortened derivative of the .223 case.

Fired from the 10- inch barrel, the 6x35mm sends its 65-grain bullet at 2,425 fps with an impressive 848 ft. lbs. This is almost as fast as the 5.56x45mm NATO bullet from a 10-inch barrel and has 74 additional ft. lbs. of energy. Compare this with 310-ft. lbs. for the 4.6x30mm cartridge and 390-ft. lbs. for the 5.8x28mm round. The 6x35mm PDW is a totally useful cartridge out to 300 meters. The 6x35mm cartridge can use virtually any .243/6mm bullet.

Currently, 20- and 30-round magazines exist for the KAC/PDW in prototype, and all have been completely machined from solid blocks of aircraft quality alloy in two halves and then welded together, and they are of unbelievable quality. However, production magazines will be molded from translucent polymer.


Reed Knight formally introduced the KAC/PDW at the 2006 National Defense Industry Association in Albuquerque, New Mexico in May, 2006. After the meetings, Reed and Trey Knight prepared to demonstrate the guns to NDIA spectators at a local Albuquerque gun club range. Arriving early, I was able to watch the two fire hundreds of rounds through the two sample guns, as well as test fire it myself.

Not only did I notice that the guns had virtually no climb when fired by Reed and Trey, but I had the same experience when I fired it. I would estimate that the KAC/PDW had roughly 75% less recoil than a 5.56x45mm NATO M4A1 Carbine. For me it felt more like firing a pellet rifle or an M4 with Simunition cartridges. No targeting was possible due to the 25- yard range we were using, but Reed and Trey Knight, and others who have tested the PDW report the guns to be capable of minute of angle (MOA) accuracy.

With the coming of the KAC/PDW, Knight’s Armament Company has capitalized the word “DEFENSE” in Personal Defense Weapons.

Specifications: Knight Armament Company Personal Defense Weapon
Country of Origin: USA.
Designer: C. Reed Knight, Jr.
Caliber: 6x35mm PDW (.243)
Muzzle Velocity: 2425 fps (739m/s).
System of Operation: Short Stroke Gas Pistons (2).
Method of Locking: Positively locked 2-lug rotating bolt (AK-type).
Type of Fire: Selective:
Semi-automatic, burst and full automatic.
Barrel Length: 10-inch (254mm) and 8-inch (203mm).
Overall Length: (10-inch bbl.);
(stock extended)
28-inches (711mm).
(stock folded)
19.5-inches (495mm).
(8-inch bbl.);
(stock extended)
26-inches (660.4mm).
(stock folded)
17.5-inches (444.5mm).
Weight: (gun only with 10-inch bbl.) 4.5 pounds (2.05 kg.).
Rate of Twist: 6 grooves, 1-in-10-inch (254mm) RHT.
Feed Device: 30-round box magazine.
Safety: 3-position safety selector.
Rate of Fire: 600 rounds per minute.
Sights: front) Flip-up post adjustable for elevation.
(rear) Flip-up aperture adjustable for windage.
(optics) M1913 top rail accommodates any
optical sight system.
Stock Furniture: Matte black polymer.
Finish: MilStd and hard-anodized matte black.
Price: To be announced.

While the KAC/PDW will be available in semi-automatic only, burst-fire and standard selective fire, there are no plans to make a 16-inch barrel “civilian” version at present, but with this new cartridge and platform, the sky is the limit. You can expect to see a proprietary hard case for the KAC/ PDW from Hardigg and I predict that you can also sit back and watch the 6x35mm cartridge live a life all its own. In the meantime, for information on all its superb products, contact Knight’s Armament Company, 701 Columbia Blvd., Dept. SOF, Titusville, FL 32780; phone: 321-607-9900, on the web at www.knightarmco.com.

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