As an old history teacher of mine once said... (I don't agree, but it's funny
)
'Back when the constitution was signed, I doubt they had any idea of what full auto guns we'd have today, there were saying, 'Everyone is entitiled to a gun to defend our country'... they had muskets, single shot, muzzleloading muskets, now... Since they meant muskets, I think everyone is entitled to a musket, I mean, seriously, can you imagine a drive by with a musket?' 
Ahhh.. but your liberal twit teacher failed to note that the military forces they were defending themselves from also had muskets.
Up until the 1930's we, the citizens; had the ability to equip ourselves with the same hardware the military had.. machine guns and all. Now, your only allowed a semi-auto rifle.. at most. That includes AK's.. they look evil.. but it's one shot per trigger pull... vs helicopters, missiles, flame throwers, artillery, and full auto rifles and machine guns.
So, in essence.. what your liberal weenie teacher told you is in a bent way; correct. We have the equivalent of muskets vs what the forces of tyranny will bring to the subjugation station.
And, they wanna take THOSE away too.