10-22 Barrel Retention V-Block: FFFTech/FFFTechnology Self explanatory. Once barrel is pressed in the receiver, install this via two 12-24 V-Block bolts. (Can be found on Amazon.com) Idk, its a friggin V-Block. Waddaya want from me; an instructional DVD? Just print the damn thing. Printer Used: Monoprice Maker Select Plus Filament Used: PLA+ Print Settings: Extruder: 218C Bed: 56C First Layer Print Height: .18mm Standard Layer Height: .14mm Wall Thickness: .40 Wall Perimeters: 6 Infill: 60% Infill Pattern: Gyroid Material Flow: 100% Hardware Needed: 2x V-Block Bolts