Shotgun cartridge case-sleeve and a cartridge made therefrom

A shotgun cartridge comprising a body including a cylindrical wall having an outer surface, an inner surface, a first end and a second end, and a base portion at said first end of said cylindrical wall defining an end plane and having an inner wall, said entire cartridge case comprising a unitary one-piece body of plastic material, said base portion including a central opening adapted to receive a primer, said cartridge including an end closure at said second end of said cylindrical wall, a wad member disposed within said cartridge and spaced from said end closure and said base portion whereby the space between said end closure and said wad member is adapted to receive shot means and the space between said wad member and said base portion is adapted to receive a powder charge, and a plurality of grooves extending axially from said end plane, said plurality of grooves including radial groove means and circumferential groove means defining a plurality of displaceable regions of said base portion defined by both said radial groove means and said circumferential groove means, whereby said plurality of displaceable regions of said base portion are axially displaceable by means of the powder charge gases released by said cartridge.