When the 2nd Amendment was written the most lethal gun available was the smooth bore musket. The inaccuracy of the smooth bore musket is what made it necessary for huge lines of men to assemble in close proximity to the opposing side and fire massive volleys of lead at each other. I’m pretty sure none of the founding fathers envisioned a day when one lone gunner could walk into a crowded theater and lay waste in numbers exceeding what it took a couple hundred men to do in 1791.