KRISS Vector

The KRISS Vector series is a family of weapons based upon the parent submachine gun design developed by KRISS USA, formerly Transformational Defense Industries (TDI). They use an unconventional delayed blowback system combined with in-line design to reduce perceived recoil and muzzle climb.

Design
The Vector's action, the KRISS Super V System (KSVS), is an articulated mechanism which allows the bolt and an inertia block to move downward into a recess behind the magazine well. The theory is that at the end of this travel, energy is transmitted downward rather than rearward, reducing felt recoil.

.22 LR, .40 S&W and 9×19mm Parabellum variants were mentioned when the gun was first released. Gen 2 variants with multiple design changes including a new 9mm variant were confirmed at the 2015 SHOT show., though the other versions have yet to materialise. The original Vector was designed to accept standard Glock 21 pistol magazines.

When fired, the barrel axis is in line with the shoulder as in the M16 rifle, but also in line with the shooter's hand. This is intended to reduce muzzle climb when combined with the off-axis bolt travel.

Variants
The selective fire submachine gun variant, the Vector SMG features a 5.5 inch barrel, folding stock, flip-up Midwest Industries back-up iron sights (BUIS) (MagPul MBUS on Gen II weapons), Picatinny rails, and three-mode selective fire (single, two-round burst, full-auto).

Three semi-automatic versions are produced for the US Market. The Vector CRB is the semi-automatic carbine with a 16 in barrel, intended for states with short-barrel rifle bans. The standard model has a folding stock (fixed in states where state law prohibits). The Vector SBR is a short-barreled version featuring the 5.5" SMG barrel but it is not capable of full automatic fire. The Vector SDP is a pistol version that has a permanently affixed cap with a sling mount in place of a folding stock. "Enhanced" versions of the CRB and SBR are also available, with collapsing M4-style stocks instead of the standard folding stock.

A second generation version of the Vector called the K10 was announced at SHOT Show 2011. This is a slightly more compact weapon based on the same Super V system. The main difference is the use of a telescopic stock that collapses into the upper receiver rather than the earlier folding stock. The cocking handle operates downward instead of horizontally. The K10 was not displayed after SHOT 2013 and its status is unknown.

KRISS is also developing a semi-automatic pistol called the "KARD", using the Super V System 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.