Abstract: Shotgun cartridge cases are disclosed which are produced from a unitary body of plastic material. The shotgun cartridge cases include a cylindrical wall with a based portion which includes a central opening adapted to receive a primer, and a number of grooves extending axially from the end plane of the cartridge case and defining displaceable regions of the base portion whereby these displaceable regions are axially displaceable by means of powder charge gases released by the cartridge. Shotgun cartridges are also disclosed.