semi auto handguns,CMMG,55ADF4E,5.56x45mm View cart “CMMG MK4 K 5.56mm NATO 12.5″ Barrel, 30rd Mag” has been added to your cart. Showing the single result Default sorting Sort by popularity Sort by average rating Sort by latest Sort by price: low to high Sort by price: high to low Sale! IN STOCKCMMG MK4 K 5.56mm NATO 12.5″ Barrel, 30rd Mag $861.79 Original price was: $861.79.$775.61Current price is: $775.61. Add to cart