Experience of several years in evaluating the additional drag of external stores shows that enough confidence exists in the standardized methods in flight tests with the most important condition of availability of individually calibrated engines. But more analysis is needed of other external stores, carriers and airplanes, especially for more statistical values concerning the interference drag. Additionally further efforts are necessary for incorporating the surely existing geometrical dependencies between stores, pylons and wing in new interference diagrams. Concerning the twin store carrier configurations, additional evaluations are necessary for other store types in combination with the already known carriers as well as for new carrier types with the aim to get more information about the double store interference factor. This is especially desirable for configurations with fairly tight spacing.