NorwegianShooter
New member
Hey. I got a couple of M16 lowers and I´m looking for the option to get at least one fitted with the new Sig MCX upper. I might opt for the SBR-option with either the sidefolder or the telescope stock. My question if really wether or not the Sig upper will run full auto seeing as it uses a different bolt carrier and being sold as civilian kits. Are the "retrofit to AR-lowers" kits already out there?