A new AWB, which I gravely doubt would be passed - I have a bet on this with a conservative buddy - could face constitutional challenge.
However, it would come up against the Heller view of reasonable restriction.
Are the semi auto military derivative guns so inherently dangerous that they could be reasonably restricted?
We might argue that they have utility for sport but is the risk (in rampages, organized gangs, etc.) too great? After all, most all hunting purposes can be handled by single shot Ruger Model 1s or a bolt gun. Carbine matches (which I love) aren't worth the risk.
The Second isn't about sport or deer or birdies.
The Second is about self-defense, defense of country and defense against tyranny.
The semi auto military derivative guns - do they contribute to these?
If I were a reasonable restriction sort of guy (say Scalia who hunts biridies with Cheney - duck - double entendre) - I might argue that you can reasonably defend your house with a handgun and pump shotgun.
You might argue for AW self-defense based on Katrina or LA Riot scenarios but would Scalia-oids buy that? Certainly the antis wouldn't. Low probability and not worth the countervailing use in rampages and crime.
Defense of country - despite judges from TX who think the UN is coming up I-35 to get them, after stopping to refuel the 1st Botswana Armored Divsion and Fighting Luxemoburg Special Forces with BBQ and chicken-fried steak in Waco - is hard to justify. We are not going to be invaded. The Yamamoto quote about WWII can't be reliably sourced and isn't evidence for such. Wolverines are animals, shoes and a superhero.
We are left with a clear justification - defense against tyranny - probably due to government gone wild. Now, tyranny can come from the left or right extremes. Spare me conspiracies based on current players. Neither current party can institute a real tyranny unless you are wearing a tin foil hat.
But, it can happen. Germany was a civilized country in 1913 but by the mid 30's become one of the greatest monsters the world has even seen.
It can happen anywhere. The social psychology is clear if the circumstances become extreme.
Thus, a reservoir of force in the general populace buffers against that. I note that genocide research indicates that minorities don't become victims if they have a reasonable chance of SD - you might get a civil war but that's horribly better than a genocide.
Would the SCOTUS buy defense against tyranny? I note one 'ahem' I debated on another forum denies that a populace could resist a government and thus saw no need to own the guns in question for that purpose. We would be shelled and bombed. However, that says a lot about the American fighting men and women - I doubt that would happen. Also, it shows an ignorance of force levels. Even our full armed forces could not occupy, so to speak, our entire country.
Some folks point to the Warsaw ghetto to say fighting against tyrants is hopeless - but the Jews didn't have preknowledge of the horror that was oncoming. Bad example.
However, if as this 'ahem' suggested - we cannot defend against tyranny, the 'ahem' has given the SCOTUS reason for an AWB. Note, it wouldn't work practically, see DOJ research.
Yes, we all could handle the vast majority of SD with SW Model 10s The rare intensive incident isn't worth the risk of the semis.
So give up using hunting, sport and even average home SD to defend the guns in question. There is a better reason.
They should be owned to protect liberty and act as an innoculation against tyranny.