An embodiment of a tubing or casing hanger seal assembly includes a first carrier ring, a first energizing ring coupled to the first carrier ring and configured to set a first seal of the seal assembly in response to the application of a first load to the seal assembly, and a first lock ring configured to secure the first seal to the tubing or casing hanger in response to the application of the first load to the seal assembly, wherein the first carrier ring and the first lock ring include corresponding angled engagement profiles for providing a radial force against the first lock ring relative a central axis of the seal assembly in response to the application of the first load to the seal assembly.