The constitutional right to bear arms was to allow the populace in general to protect themselves from ALL enemies.
I have a problem when one of those possible enemies is allowed to determine what is 'reasonable'.
Had the British understood the colonies potential for guerrilla warfare, they would have outlawed long guns. They fully expected to meet their opponent on the field of battle in an 'honorable' formation. We, however, hid behind trees & rocks.
The founders were obviously thinking of the recent conflict winning our freedom, and the possibility that it would be necessary to do so again. The balance of power assures freedom.
Let us pray that it never becomes necessary, but be always prepared if it should.
Thomas Jefferson put it best:
"And what country can preserve it's liberties if their rulers are not warned from time to time that their people preserve the spirit of resistance? Let them take arms. The remedy is to set them right as to facts, pardon and pacify them. What signify a few lives lost in a century or two? The tree of liberty must be refreshed from time to time with the blood of patriots and tyrants. It is it's natural manure."