A grinding machine has a shearing chamber that includes one or more edges that provide fulcrum points against which frozen block of material, such as frozen blocks of meat, can be held against during a reduction or shearing process. The edges may be arranged to limit the advancement of reduced blocks of material to provide more control on the size of the ground material that is ultimately output by the grinding machine. The grinding machine may also include an expansion zone into which reduced blocks can be temporarily held to accommodate volume increases during the reduction process. A feed screw advances the frozen blocks through the shearing chamber and includes pressure fighting to help shear material from the frozen blocks. The feed screw may include a knife holder that provides support for a knife held therein against the lateral forces experienced by the knife as the knife shears material adjacent the orifice plate.