Arms = weapons. Second amendment talks about arms, not firearms. It's not silly to ask the question.
Though your answer that the Amendment should only be interpreted to allow individual ownership of what an individual militiaman might carry is certainly interesting. Are we willing to follow that logic all the way through to its conclusion?
When the Constitution was drafted "arms" specifically referred to weapons which could be carried and were used while being held. Consider Article VI of the Articles of Confederation (which immediately preceded the Constitution). It requires States to stockpile both "arms" and "field pieces". Field pieces are artillery; special weapons of war requiring multiple men to operate. The 2nd Amendment however, is a protection only of "arms", which were smaller, lighter weapons personally carried and operated by individual soldiers. One of many ratification debates touching on this subject was whether or not the government should have a standing army. The compromise Constitutionally enshrined the militia as a separate unit of national defense. Separate, but on par with. Which is why I believe the term "arms" extends to those handheld weapons common to an ordinary infantryman.
