The correct mil. spec. cleaner/lubricant for AR15/M16 rifles is "Break Free" with CLP. However, we realize many people use other solvents, and we sell a comparable product from Tetra. The ammonia in Sweet's will not harm the chrome lining of the barrel, but long exposure may damage the receiver's finish. The use of a chamber rod guide should keep the solvent off the receivers, if you remove the lower when cleaning.