Small Base Sizer Die Features The Forster .308 Small Base retains same headspace as the 308 Win.; however it reduces case body diameter by .003 from the 308 Win. This sizing is sometimes required for the proper action of ammunition intended for use in automatic semi-automatic slide pump and some lever-action rifles. Small Base Sizer Die Specifications Brand: Forster Model: Small Base Sizer Die Reloading Caliber: 308 Cal Reloading Die Type: F.L. Sizer Type: Rifle