Abstract: A coupler for a railway car coupling system includes an elongated shank terminating in a generally rectangular butt portion. The shank is generally octagonal in cross-section for strength, and the coupler butt portion has an end face provided with a convex spherically radiused contact area. The contact area is adapted to cooperate with a follower having a correspondingly concave spherically apertured recess. The butt portion end face is also provided with relieved corners to reduce wear and scoring thereon as it contacts and rotates against the follower. Relieved portions are provided in the coupler butt portion adjacent a transverse pin receiving aperture for accommodating limited angling of the coupler within the coupling system.