The stability of both regular reflection and Mach reflection wave configurations in pseudosteady flows has been investigated by applying the principle of minimum entropy production, in a way similar to that done by us in Part I of this study [Li and Ben-Dor, J. Appl. Phys. 80, 2027 (1996)] where the stability of steady flow reflection configurations was considered. As a result, it was found that Mach reflection wave configurations are stable inside the dual solution domain, although, based on the state of the art when this study started, they were considered not to be stable. Consequently, a new general transition criterion from regular to Mach reflection was proposed. With the aid of this criterion the domains of regular, direct-Mach and stationary-Mach reflections, in the domain of the incident shock-wave Mach number and the reflecting wedge angle, were reestablished. All the analytical findings were supported by experimental results from different sources.