It used to be you had iron banner was about every 4 weeks so once a month then we had the very long hiatus that went from the last one of heresy to it's release in rise of iron. With the mid-season update making it sound like it was going to be this major event dealing with it hence calling it Ash and iron they screwed the pooch on it released the Hand cannon in a mediocre state with very bad stats that they actually went through and retroactively fixed but never had an iron banner since for anyone that didn't keep one or get one. It just is sad that content that could be being played isn't being offered when there's already very little to do and then they totally botched the whole way they handled iron banner rewards with the single gun event card way of doing it instead of the way it used to be with a large poll of weapons similar to trials.