KAK Industry bolt carrier group for .224 Valkyrie and 6.8 SPC. Chrome-lined and phosphate finished. The workhorse of KAK Industry's BCG portfolio, this product is made to provide years of unquestionable reliability. All KAK Industry BCGs feature an M16 (Full Auto) carrier profile, meticulously machined from 8620 steel, properly heat treated and ground to exact tolerances. Other components include: a single piece billet-machined 4140 extractor, phosphate finish on components.