STEN MK3 SEMI AUTO tube that can work with our standard horizontal feed bolt (MK3SAK) or our vertical feed bolt (MK3VSAK).  This tube has 3 overlapping patterns around the barrel shroud that you can choose from or customize (ORIGINAL LAYOUT, VENTED LAYOUT, and FLAMES!)  The high quality template is CAD drawn and is glued to aerospace grade 4130 DOM tubing. You will need a dremmel tool or milling machine and a welder to assemble. This design has been classified by the ATF as a firearm and not a machinegun. This is NOT a receiver and does not require a FFL for purchase.