It's citizens who make up a militia
The authors of the Bill of Rights knew exactly what they intended the Second Amendment to mean, and it was definitely not to have a citizenry which was powerless against a tyrannical government. We learned in U.S. history class about the Minutemen who were private citizens who formed the first resistance to the British army. They were essentially the militia of the day, and like militiamen before and since, were expected to provide and maintain their own personal weapons. The Revolutionary War was well underway before Congress found, and arranged, funding to establish an official army. Prior to that, the colonists/combatants would return home at their discretion for planting, harvesting, etc.
We would embark on a dangerous precedent to start arbitrarily tampering with the Bill of Rights. I have no doubt that there would soon be those who would offer “justifications” to modify, and alter the intent of others. Perhaps those who are so quick to vilify the NRA, and demand sweeping restrictions on private gun ownership, would be better served by following the NRA's insistence on strict enforcement of the 22,000-plus current gun laws, and that gun law violations be punished to the limit of the law. They might also look at what transpired in those countries which have outlawed private firearms, and at the gun homicide rates in the U.S. cities with the most stringent gun restrictions and prohibitions.