Semi-Auto Case Gauge .308 - Optimized for semi-automatic rifles the second generations JP Case Gauge guaranties function of your ammo. If it fits our gauge it will fit even a minimum-depth SAAMI chamber without interference. - Take comfort that your ammo will never hold you back. - Features: - Specially calibrated to ensure function in semi-auto rifles - Guaranties ammo fit in a minimum-spec SAAMI chamber - 416 stainless steel construction for wear resistance and greater longevity - Also gauges all features of .260 Rem. short of concentricity runout - American made