The American company Knight's Armament Co. was no exception. (KAC), known for its original designs. The first studies related to the concept of PDW were made by KAC back in the eighties, but then all the work stopped at the stage of studying the prospects of a new weapon. In the future, KAC several times returned to the idea of creating its own version of PDW, but this weapon did not have much success and did not come out of the test stage. The company presented the first “full-fledged” project of its PDW only in 2006 year. The new weapon has received a straightforward name that fully reveals its essence - KAC PDW.
Characteristics of the KAC PDW system do not allow unambiguously to classify it as a submachine gun or automatic rifle. Nevertheless, some features of this weapon allow us to attribute it to both submachine guns and machine guns. But due to external similarities and some features for convenience, we will call KAC PDW an automatic machine, not forgetting, however, that this rifle system is a “Personal weapon of self-defense”.
A characteristic feature of almost all types of weapons class PDW are original ammunition, which is a "hybrid" of the pistol and intermediate cartridge. In order to ensure the required characteristics of fire in combination with small dimensions and weight, gunsmiths reduce the caliber of bullets, while maintaining a relatively high initial velocity and muzzle energy. For the KAC PDW, a new original cartridge was also chosen - 6x35 mm TSWG.
The 6x35 mm TSWG cartridge was developed in the first half of the 2000s by Hornady. This ammunition has a relatively short bottle-shaped sleeve, 35 mm long, made of brass. The cartridge with a total weight of 10,1 g is equipped with a 6 mm caliber bullet with a weight of 4,2 g. According to some data, the TSWG cartridge in its basic configuration is equipped with an expansive action lead shell bullet. Due to this, with a small caliber should provide a high lethality. At distances up to 200-300, the cartridge 6х35 mm TSWG is not inferior to the standard NATO intermediate ammunition 5,56x45 mm for a number of characteristics.
The KAC PDW was originally designed for use with the TSWG cartridge, and its design is based on some technical solutions typical of US automatic weapons. So, the receiver of the weapon is divided into two parts, as on the M16 and M4 rifles. In the upper part of the box is mounted the barrel, and also the shutter mechanisms are located. At the bottom there is a trigger mechanism and the receiving shaft of the store. The lower part of the receiver is made on the basis of the corresponding details rifle M16.
Like the bulk of modern automata KAC PDW uses vapor-automatic. Above the barrel there are two venting tubes and two gas pistons. According to some reports, two gas engines are used to increase the reliability of automation when using a relatively low-power cartridge, giving a small amount of powder gases.
The bolt carrier and return spring are located in the upper part of the receiver. An interesting feature of the KAC PDW is some features that are not typical of American automatic rifles, but of Soviet / Russian weapons. So, the barrel locking of this weapon takes place by turning the bolt, the design of which greatly resembles the corresponding units of Kalashnikov assault rifles. The AK series weapon also recalls the location of the return spring: it is completely hidden inside the receiver.
The KAC PDW is equipped with a rifled barrel with a length of 10 or 8 inches (254 and 203,2 mm). On the outer surface of the trunk there are numerous hemispherical notches. It is argued that this allows the barrel to be lightened, as well as to improve its cooling during firing. A muzzle compensator is installed on the barrel, designed specifically for the KAC PDW, taking into account the characteristics of the 6x35 mm TSWG cartridge.
The trigger mechanism is located at the bottom of the receiver. It allows you to fire both single shots and bursts. Flags of the translator of fire are on both sides of the receiver, above the pistol grip and are designed to switch with your thumb. The translator of fire has three positions: blocking mechanisms, single and automatic fire.

For ammunition automatic machine Knight's Armament Co. PDW uses original detachable box magazines on 30 cartridges. By design, they resemble the standard NATO shops for 5,56x45 mm cartridges, but are noticeably smaller. The store is placed in the receiving shaft of the machine, also resembling those used on American automatic rifles. Shop latch unified with existing weapons.
Placing all the units inside the receiver allowed the butt of the weapon to be collapsible. If necessary, it swivels and fits along the right side of the machine. The location of the triangular frame butt does not interfere with the use of weapons or the release of spent cartridges.
In accordance with recent trends, the KAC PDW machine has several universal Picatinny rail, allowing it to be equipped with various additional equipment. So, on the upper surface of the weapon there is a bar almost the length of the receiver. In the basic configuration on this bar is set standard diopter sight and front sight. If necessary, they can be replaced by any other sighting device that allows installation on a universal mount.
Machine KAC PDW has no pronounced forearm. Instead, the weapon has a forward-drilled perforated barrel casing, which is integral with the receiver. On the side surfaces of this casing, two Picatinny rails are installed, which can be covered with special plastic covers. The fourth bar is located under the barrel cover and can also be closed with a lid. On most of the published images, the machine is equipped with a front "tactical" handle mounted on the bottom bar.
"Personal defense weapon" KAC PDW in appearance, purpose and some characteristics like automatic rifles and machine guns. At the same time it has much smaller dimensions and weight. So, the length of the KAC PDW with a 10-inch barrel with a folded butt is equal to 495 mm. When the stock is folded, the length exceeds 730 mm. Using a barrel with a length of 8 inches further reduces the size of the weapon.
KAC PDW (10-inch barrel) without ammunition weighs only 1,95 kg. A closed magazine increases the weight of the weapon by about 400 g. Thus, the machine gun with 3-4 magazine ammunition weighs no more than 3,5-4 kg, which in combination with small dimensions makes it easy to carry and use.
Vapor automatics of the weapon provides firing rate up to 700 shots per minute. When using an 10-inch barrel, the initial bullet velocity exceeds 740 m / s. The target range of the weapon is 300 m. It is stated that when shooting at such distances, the KAC PDW is not inferior to other modern American rifle systems using the 5,56x45 cartridge mm.
The KAC PDW shooting complex was first introduced in the 2006 year and has since been repeatedly demonstrated at various weapon shows. The weapon was offered to customers in two configurations that differ from each other in barrel length. The promotional materials focused on the favorable ratio of the size of the weapon and its firepower. In particular, it was argued that when folded, the KAC PDW does not prevent the fighter from leaving the combat vehicle, but allows him to immediately enter into a firefight with the enemy.
However, it seems, the project Knight's Armament Co. PDW suffered the same fate as many other original developments in the field of small arms, including the Personal Defense Weapon class. Eight years have passed since the first demonstration of the KAC PDW submachine gun, but so far no reliable information about the procurement of these weapons by the armed forces or security forces has appeared. According to some reports, police departments of several US states have shown interest in KAC PDW and even expressed a desire to test this weapon in practice. However, until now, the KAC PDW system and the cartridge 6х35 mm TSRW have not been adopted anywhere.
Admittedly, the KAC PDW weapon is of some technical interest. Engineers company Knight's Armament Co. managed to create a weapon with firepower, close to automatic rifles, in the dimensions of a submachine gun. In addition to the characteristics of this system, it should also be noted an interesting approach to the layout of weapon units. In terms of its architecture, the KAC PDW is reminiscent of the M16 and M4 rifles in service, which probably should somewhat simplify the training of shooters and the use of weapons. However, these interesting features of the KAC PDW, it seems, could not interest potential customers and help the weapon to reach mass production.
On the materials of the sites:
http://knightarmco.com/
http://defensereview.com/
http://armoury-online.ru/
http://raigap.livejournal.com/