The main argument is that in the late 18th and early 19th Centuries, the federal government depended on defense from attack primarily from the state militias. Most states required a citizen to have arms to react to a call up, since few armories existed. That's not the case today.
And for you MAC, it's fine to say that the 2A guarantees a RTKABA but you have to expound a bit. Is the RTKABA only indicated for squirrel hunting?
Actually, it would include pheasant, quail, rabbits....
Seriously, laws should not prohibit law abiding citizens from owning reasonable firearms for their own protection if not for hunting. The issues of reasonable and law abiding are the ones most apt to look to the courts to solve. We agree that such rights exist, even though the original reason for the amendment no longer exists, but the issue of how far governments can go in curtailing those rights for the protection of society as a whole is more complex than some here see it.
While I do know we have rights to own and carry firearms, I'm not ready to concede those rights include weapons of every type. I think it is reasonable for governments to regulate certain types of weapons and ammunition that have capabilities not even imagined by the founding fathers. If the judge in this case finds for the prosecution, I would lose no sleep over it. If a judge finds that a handgun or rifle were not permitted a law abiding citizen, I would loose much sleep.
The free state referenced in the 2nd amendment means a society free of tyrannical government. That reason still exists. Government becomes more tyrannical as it smothers citizens with unjust regulations. The 2nd amendment is the only thing that prevents the government from running totally roughshod over the people.
You need only look at what happened under Hitler, Stalin, Mao and Pol Pot to comprehend what happens when the citizens are disarmed and the government is free to do as it pleases.