RCBS Single Stage shell holders are built from hardened steel and designed to properly align the case with the reloading die in single-stage and turret presses. They're sized to fit specific case heads and capture 0.125 inch of the case head for proper SAAMI headspacing. This model is compatible with the following calibers: 257/6.5-300/207/7mm/300/340/ Wbthy Mag; 264/30-338/300/338/458 Win Mag; 6.5/7mm/8mm/350/416 Rem Mag; 7mm Shooting Times Westerner; 300/338 RCM; 300/375 H&H Mag; 308 Norma Mag; 9.3mmx74 Rimmed; 357/416 Ruger; 450 Marlin; 458 Lott; 460 S&W.