A power block for holding a welding gun power pin has a receiving structure which defines a bore which receives and holds a welding gun power pin. The power block further includes a projection movable between at least a first position and a second position. When the projection is in the first position, the projection extends at least partially into the receiving structure cavity. When the projection is in the second position, the projection generally does not extend into the receiving structure cavity. In some embodiments, the projection has a generally straight line distal edge. In other embodiments, the projection has a generally arcuate distal edge.