Civilians have no "USE" for one?
I beg to differ. I don't think it says anywhere in the Constitution that we can only own guns if we have a "USE" for them. As far as utility (a word I think is more appropriate than use). I've told the board this a few times before but I used to work Animal Control where I had need to fire so many times in a row that it helped to have a second person there for firepower with the 870. There was one utility.
Another is somebody who doesn't WANT to carry around a handful of shotgun shells but also doesn't like the idea of running out. Home invasions, gang shootouts in your neighborhood, and riots come to mind.
While these are narrow instances, it should also be noted that the utility for Criminals of such a cumberson aparatus is very limited. Criminals want concealability and something that goes bang when you pull the trigger and isn't difficult to reload. Very few would have the desire, funding, or knowhow to modify their own guns (usually stolen) for only a marginal increase in utility.
