The founding fathers intent for the Second Amendment was clearly so that the people could defend themselves against tyranny - including from and especially from their own government.
The people would therefore need to have the right to keep and bear arms that were equivalent to the governments and armies that they may need to fend off.
As that is the goal of the Second Amendment, then how can we possibly BAN weapons that are equivalent to those of the potential enemy that we'd need to fight?
Founding Father's Quotes:
"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. " - Thomas Jefferson
'The tree of liberty must be refreshed from time to time with the blood of patriots and tyrants." - Thomas Jefferson
"I hold it that a little rebellion now and then is a good thing, and as necessary in the political world as storms in the physical. Unsuccesful rebellions indeed generally establish the incroachments on the rights of the people which have produced them. An observation of this truth should render honest republican governors so mild in their punishment of rebellions, as not to discourage them too much. It is a medecine necessary for the sound health of government." - Thomas Jefferson
"No free man shall ever be debarred the use of arms." - Thomas Jefferson
"Let your gun therefore be the constant companion of your walks." - Thomas Jefferson
" I presume he is a gun-man, as I am sure he ought to be, and every American who wishes to protect his farm from the ravages of quadrupeds & his country from those of biped invaders." - Thomas Jefferson
"Rebellion to tyrants is obedience to God." - Thomas Jefferson
"They that can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety." - Benjamin Franklin
"Arms in the hands of individual citizens may be used at individual discretion for the defense of the country, the over-throw of tyranny, or in private self-defense." - John Adams