The Gun Boy made my Wild Hare has a 54" case which is long enough for a Beretta 391 with a 30" barrel and extra long extended chokes. It's about $30 or so. Beretta sells that case under their own name.
Another soft case style that's hard to find is one that clears high mounted scopes or very long scopes. These used to be common, but my guess is the marketing bean counters simply said they could save money making a "one size doesn't fits all" case to save material and other costs.