Modular Guns: Assembling a SIG USW-320
This video details the assembly of a custom SIG USW-320, a modular pistol build. It highlights the SIG P320's modularity, where the Fire Control Unit (FCU) is the serialized part. The build incorporates a B&T USW chassis, an Agency Arms slide with a compensator, and a Trijicon RMR optic. Crucially, it notes that adding a folding stock to the USW-320 requires NFA registration as a Short Barreled Rifle (SBR).









