This study investigates the influence of the nozzle geometry on the mean flow field of an annular swirling jet. The nozzle geometry consists of a sudden expansion with step size s followed by a divergent with opening angle alpha and axial length L. The inner dimensions of the nozzle are changed via s, L and alpha and in total 87 different nozzle geometries are investigated. For each geometry the mean flow pattern as a function of the swirl is determined experimentally using pressure measurements. In these measured pressure diagrams, different regions are identified and each region corresponds to a different flow pattern. Up to four different flow patterns can exist depending on the combination of s, L, alpha and swirl number: Closed Jet Flow, Open Jet Flow Low Swirl, Open Jet Flow High Swirl and Coanda Jet Flow, and hysteresis exist in the flow patterns upon increasing and decreasing the swirl for certain nozzle geometries. A stability diagram is presented in the ( s/L, alpha)- plane. This region contains the combinations of s/L and alpha, which give the highest number of different stable flow patterns. The information in this article can serve as a database for the design of nozzles in cold flow applications as well as in swirl-stabilized burner heads.