A cutting insert for mounting in a socket on an insert holder of a milling cutter. The cutting insert has opposing top and bottom surfaces and a peripheral surface extending therebetween, forming one or two cutting edges. The peripheral surface has a front arcuate surface and a rear surface. The rear surface has a protuberance that extends in a direction away from a central region of the front surface. The protuberance is located in the socket. The socket includes a first socket side abutment surface for providing primarily axial support for the cutting insert against cutting forces acting in an axial rearward direction during a milling operation.