You are incorrect. The citizens of this country created a government, and cannot give powers to the government that they do not possess them selves. The Second amendment was put in place specifically so that if the government that had just been created with the constitution somehow became tyrannical, despite the safeguards in that document, that the people would have in their hands the means with which to overthrow it in the same manner as the drafters and ratifiers of the Second Amendment had just overthrown the English government.
Additionally, if you look at article 1 section 8, among the powers given to the Congress is to issue Letters if Marque and Reprisal. This is congressional authorization to civilians vto attack enemy shipping and other forces during wartime when the (purposely small) standing army and navy didn’t have sufficient forces on hand to do the job. How, pray tell, does one take on enemy forces without having equivalent weaponry? Note that the Continental Congress issued many Letters, as did Congress during the War of 1812 and afterwards, so the power is not unused. Just as John Hancock has cannon-armed ships he used to fight the British Navy, so today should individuals have the ability to have similar modern weapons.
Which is precisely what I stated.
The 2nd Amendment is a hedge against a tyrannical government.
Only, I said it more succinctly.