A self-centering nock is provided for use in a well-balanced nock-arrow or nock-bolt assembly. The self-centering nock includes compliant projecting protrusions or compliant arms that are substantially rotationally symmetric about a cross section normal to a main axis of the self-centering nock. The compliant projecting protrusions or compliant arms may be received in bolts that have bores of differing internal dimensions.