Little background. Bought a SIG M400 in 300 BLK. Registered the SIG lower as an SBR. Its not for sale. Built a new lower from an Anderson lower receiver and magpul lower parts kit and trigger mods for 3 lb pull.. Put them together and this 16" complete rifle is for sale. So... Anderson lower . SIG Sauer 16" M400/300 Blackout upper ( maybe 600 rounds through it ) with Magpul forend stock. SIG chrome lined BCG, Ambi safety, One 40 round magpul mag included. Super tight upper to lower fit. That upper has digested everything Ive tried running through it from lightweight supers to heavy subs and even mid weight subs. Price: $600 gun alone with magpul BUIS. Will trade gun for Ruger Stainless Old Army Black Powder six gun. Prefer fixed sights $750 for the gun and Nikon P-300 scope and Nikon mount Add another $100 if you want a slidefire stock set with it. Pretty fun to play with and more reliable than you'd think. FTF in Oregon before this revenue enhancing transfer silliness kicks in.