I have never read of the 'problem' in any of the smaller gauges, only the 12. I have yet to actually see one or to have personal knowledge of anyone actually having the problem. From what I have read, I am led to think it involved, in addition to what has already been mentioned, picking up previously reloaded hulls and or hulls that may have been fired in overly large chambers or semi-autos with return springs worn beyond their service limits. There is of course no way to prove nor disprove that, but it is my strong suspecion.
On any break-open gun it is a good habit to look and see that the bbls are unobstructed when loading a round or rounds.
On a personal experience level, I have found a few HS28's [<20 total and none recently] new brass heads loose after being fired. The hulls may or may not have been fired in one of my guns or tubes. I just don't know.
I have reloaded many HS 12's since their introduction and never had the first issue with one and I do not worry about it. If you are going to worry about the hull's base wad, then you are perhaps better to use a dif hull as any unneeded distraction is a negative when shooting.
As an aside, I will say that I have concluded that many hulls found with their heads bulged and the base convex are from having been fired in semi-autos that have return springs that are beyond their service limit and do for replacement. Any hull that I discover with either sign [bulged head or convex base] I discard rather than reload and I do not care if it looks to be a once fired hull or not.
