Unfortunately (or fortunately) the courts don't recognise common sense per se as authority for an argument. Often, what may be common sense to you may not be common sense to someone else.
In interpreting the constitution, the Judge has to put himself into the mind of its drafters and come to a view as to what was intended if the plain words are ambigious or yeild a manifestly unjust result. Often this can be the judge exercising his or her common-sense on the issue, but not always as there is precedent to consider as well.
As Toad has pointed out, there is a lot of litigation about the scope of the 2nd Amendment, and it's just one of those areas where different people have different views as to what the answer is. It looks like it's an area in which there are no easy answers particularly because the political and social landscape have changed so much since the 2nd Amendment was drafted that many of the reasons that preyed on the drafters' minds then are irrelevant now.
It's a bit like trying to put a modern meaning to 'Six days you shall labor and do all your work. But the seventh day is a sabbath to the Lord your God; you shall not do any work—you, your son or your daughter, your male or female slave, your livestock, or the alien resident in your towns. '
