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; a special "MagEx 30" kit was available to convert a factory 13-round .45ACP Glock magazine to an extended high-capacity version, though this is now marketed as a "25+" round kit. The newer 9x19mm versions instead use standard Glock 17 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.
The selective fire submachine gun variant, the Vector SMG features a 5.5 inch barrel (with an option of a 6.5-inch barrel on the Gen II version), folding stock, flip-up Midwest Industries back-up iron sights (BUIS) (MagPul MBUS on Gen II weapons), Picatinny rails, and two or three-mode selective fire (single, optional two-round burst and full-auto).
Three semi-automatic versions are produced for the US Market. The Vector CRB is the semi-automatic carbine with a permanently-affixed extension to the standard 5.5-inch barrel, extending it to 16-inch (410 mm), 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 same barrel as the SMG 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. The newer Gen II version features a redesigned pistol grip and trigger, optional factory Cerakote coatings in olive drab or flat dark earth, in addition to the original flat black, and has the swing angle of the safety lever reduced from 120 to 45 degrees. The Gen II also eliminates the opening above the barrel for the original weapon's optional Surefire weaponlight, since these are no longer manufactured. The Gen II version is also capable of being converted to 9x19mm Parabellum by replacing the lower receiver. "Enhanced" versions of the Gen II CRB and SBR are also available, with collapsing M4-style stock adaptors instead of the standard folding stock (with a Magpul UBR stock included) and a square barrel shroud for the CRB, though these accessories can also be purchased separately.
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. As TDI, KRISS also announced a 12-gauge shotgun called the MVS and a .50 BMG heavy machine gun using a double Super V mechanism called the "Disraptor," but the Disraptor has not been mentioned since their name change, while the MVS was removed from the TDI website in late 2009.