This paper deals with the shock reflection process at plane walls (wedges) which is known as pseudo‐steady. Questions still arise concerning the transition from regular reflection to irregular reflection, when the experimental transition data are compared to von Neumanns theoretical predictions. Recently several authors have shown experimentally that for weak incident shocks the transition takes place at wedges with inclinations at which the corner signal is able to catch up to the reflection point (sonic criterion). The paper intends to confirm this result for stronger incident shocks by the evaluation of visualized experiments. Furthermore it will be shown, by using gage measurements, that the corner signal is followed by a rather intensive rarefaction wave. This wave strongly influences the afterflow region of the reflected shock. The boundary conditions of the von Neumann Theory are discussed in light of this, and an approach by Skews is quoted.