This Impact Precision 777R action has an integral rail and lug. Like the Impact short action, the 777R has been machined with the extremely tight tolerances that we have been known and respected for. Indexing and headspace will be held to the same standards we have been known for, allowing for prefit barrels. FeaturesBoth BDL and DBM CompatibleWill Feed CIP Length Cartridges20 MOA Integral RailMini M16 Extractor1 1/16x16 TPI Class 3 Threads.700" Diameter BoltInterchangeable Bolt Knobs/Handles1.350" Diameter BodyIntegral Recoil Lug90 Degree Bolt Throw