A rotary knife includes a rotatable annular blade. The blade includes a blade wall presenting an annular inner surface terminating at a cutting edge. The annular inner surface includes a first section and a second section, with the first section extending from the cutting edge and the second section being located further from the cutting edge than the first section. The first and second sections define first and second angles, respectively, relative to an imaginary plane transverse to the axis about which blade rotates. The second angle is greater than the first angle.