visual comparison of MK1 vs MK2 both purchased in Jan 2017 from PA. Comparing side by side, MK1 appear slightly taller, skirt is slighter more flared, wider at bottom edge and if you turn it over, the concavity of the hollow base goes just a little deeper. It also requires slightly more force to close the lever when loading an MK1.
ive never shot them from an Mrod so cannot tell which works better with it.