Janice - The second amendment was to mollify Anti-Federalist sentiment (defeated at the time of the ratification of the Constitution) which had been focussed by the militia interests of some New England states, especially after problems with out of control elements of militias in, for example, Massachusetts. The phrase "to keep and bear arms" was drafted purely in reference to the existence and regulation of state militias as was clearly shown by the major contemporary debate being concerned with a possible exemption for citizens on grounds of religious conscience. The whole 'constitutional' basis for the claims of the NRA is historically and, speaking as a law graduate as well as a historian, legally nonsense. There's an excellent article on this to be found at
http://www.saf.org/LawReviews/FinkelmanChicago.htm