CMC's propriety In house machining" production and Quality control inspection process's allow us to attain an ultra-precise barrel with enhanced slide fit & lock up for improved accuracy. CMC's barrels are 6 groove" cut rifled" 1:10 Twist Right Hand" fully QC inspected" double honed (rough and finish) to produce the smoothest bore possible" with a Max Roughness Average (RA) of 12. Finished bore dimensions are held to +/- 0.0005" tolerance from nominal groove and bore dimensions but the dimensions are uniform to within 0.0002 for maximum consistency" accuracy and quality. SAAMI" Match Grade specification chambers" precision cut and finished to a maximum Roughness Average (RA) of 16. The pre hardened 416R stainless steel is stress relieved to an exacting recipe after rifling and final hardness is 38-42 Rockwell C before final barrel profile machining is completed. Barrels are bead blasted to create a satin finish prior to plating.