Image Number 4 for United States Patent #6505560.
A spring disc includes a contiguous outer ring including a first plurality of holes and having a contiguous, upwardly curved portion having an outer edge. A middle ring encompasses a second plurality of holes, and a contiguous inner ring, is encompassed by the outer ring and the middle ring. The inner ring surrounds a central aperture sized to accommodate installation onto a cartridge case member, where the outer ring, inner ring and middle ring operate together so as to support the cartridge case by evenly distributing stresses when installed on a cartridge case. A taper angel .theta. is built into a bottom with a value of about 1.degree. as measured from the bottom extending radially from the center of the inner ring to the outer edge with reference to a plane parallel to an imaginary plane overlaid on the contiguous outer edge.