The KRISS Vector series are a family of submachine guns developed by KRISS USA, formerly Transformational Defense Industries (TDI). They utilize asymmetrical recoil and in-line design to reduce recoil and muzzle climb.
The Vector's patented action was originally designed 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 series are 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". A variant chambered for the .40 S&W round has since been released as well.
The Vector's barrel is in line with the shooter's shoulder as in the M16 rifle and German FG42, but also in line with the shooter's hand as with many target pistols. Combined, these factors are claimed to reduce felt recoil and muzzle climb by eliminating the distance between the shooter's hand and the bore axis.
It comes with backup iron sights and a rail for mounting optics.