One thing to keep in mind, the 6.8 SPC is just that, a Special Purpose Cartridge. It was never intended to replace the 5.56 Nato as a general issue cartridge. What it is designed to do is give more umph during urban warfare without too much limitation on range while still operating on the AR platform. Personally I think the Russians already had the perfect cartridge to do just that. 7.62x39mm is one hell of a combat cartridge.