Kriss Super V

The KRISS Vector  series is a family of NFA and non-NFA weapons based upon the parent submachine gun design developed by KRISS USA. KRISS USA is formerly known as Transformational Defense Industries (TDI). They utilize asymmetrical recoil and in-line design to reduce recoil and muzzle climb.

Design

The Vector's action was originally developed by French engineer Renaud Kerbrat. This action, the so-called Kriss Super V, is an articulated mechanism which allows the block and bolt to recoil off-axis into a recess behind the weapon's magazine well. The Vector family of weapons is the first to use this action; the company claims the .45 ACP chambering was chosen to demonstrate that the action could "tame" such a powerful round. Variants chambered for the .40 S&W and 9×19mm Parabellum round are currently in development. All KRISS Vectors operate with standard Glock magazines with the .45 ACP caliber weapons using the 13 round G-21 magazine.
The Vector's barrel is in line with the shooter's shoulder as in the M16 rifle, but also in line with the shooter's hand as with many target pistols. Combined, these factors reduce felt recoil and muzzle climb by eliminating the distance between the shooter's hand and the bore axis along with the action of the Super V Mechanism.

Variants

The selective fire sub-machine gun variant is marketed as the Vector SMG, and features a 5.5 inch 16×1 left-hand pitch threaded barrel, folding stock, flip-up Midwest Industries MBUIS iron sights, upper and lower Picatinny rails, and selective fire for three modes (single, two-round burst, full-auto). The SMG is an NFA weapon and is not available for purchase for the general population.
KRISS USA also produces three semi-automatic versions of the Vector that are for sale to eligible parties in the US. The Vector CRB/SO is the semi-automatic carbine version of the SMG with a 16-inch (410 mm) barrel. "CRB" stands for carbine and "SO" stands for Special Operations. The standard model for 45 states comes with a folding stock with the option of a fixed stock in states where state law prohibits folding or collapsible stocks (California, New York, New Jersey, Connecticut, and Massachusetts).
Similarly, the semi-automatic short-barreled rifle (SBR) version is labeled as Vector SBR/SO. It is nearly identical in fit and form as to the SMG. The only difference is in function: it is not a machine gun and thus does not have an ambidextrous selector switch.
Of current production weapons, there is also an ATF-classified pistol variant of the weapon platform. This is the Vector SDP. "SDP" stands for Special Duty Pistol or Security Detail Pistol. It is essentially identical to the SBR except it has a permanently affixed cap instead of a folding stock.
An updated second generation version of the Vector called the K10 has recently been announced and shown to the firearms community as of SHOT Show 2011. This .45 ACP weapon also uses Glock 21 magazines and is a slightly more compact sister weapon that utilizes the same Super V mechanism. The largest known functional difference is the use of a metal, telescopic stock that will collapse into the upper housing rather than the injection molded plastic folding stock of the Vector's. It is also purported that the safety and fire selector switches will be combined. The cocking handle also goes downward instead of horizontally.
KRISS has announced in the past that they have looked into adapting the Super V system for higher-power cartridges in the future, with mention of a 12-gauge shotgun and a .50 BMG heavy machine gun called the "Disraptor" which is planned to use a double-sided, horizontal version of the Kriss mechanism.
KRISS is also developing a semiautomatic pistol called the "Kard", utilizing the Super V mechanism in a much smaller package to minimize recoil and muzzle rise in 9mm Parabellum and .45 ACP calibers. It will not have a blowback slide; instead it has a T-shaped cocking handle on the rear.