a method of injection moulding a plastics container 1 having wall 2 of substantially uniform thickness using an injection mould 10 with an unsupported core 12 is disclosed . a small sliver 17 is removed from the free end of the core 12 of the mould 10 from that side of the wall which is thinnest . as a consequence on the next injection more plastic flows in that direction . repeated optical inspection of the containers enables a balance to be achieved in which slightly asymmetric injection conditions are balanced by a slightly asymmetric container base with the result being a container with substantially uniform wall thickness .