a can end having a countersink bead , an inclined chuck wall and a strong seam , resists distortion from its circular profile when subjected to thermal processing or when packaging carbonated beverages . this high hoop strength affects the manner in which the can end ultimately fails when placed under extreme abuse conditions , even if buckle pressure performance is within industry specified standards . the can end of the invention has control features introduced which control the failure mode whilst maintaining specified buckle pressure performance . in one embodiment , the control feature comprises expansion of the countersink bead to act as a trigger for local peaking , together with a groove in the chuck wall which prevents the peaking force from being concentrated at a single point which could result in leaking by the production of a pin hole .