Spikes Tactical AR-10 .308 Cold Hammer Forged Barrel. Chrome lined and cold hammered forged for AR-10 platform. 7.62 NATO chamber with a rifle-length gas system. M4 style ramped barrel extension. Mil-Spec phosphate coating. Available in two lengths: 18 inch and 20 inch, both with 1/12 twist. Threading: 1/2x28. Package contents: Spikes Tactical AR-10 .308 Cold Hammer Forged Barrel.