In the USSC case U.S. v Miller, the government never contested that Miller was a member of the irregular militia, the case hinged on whether his shotgun was a military weapon. If anyone had shown up to defend the case and present evidence that short-barreled shotguns were used in battle, Miller would have prevailed and perhaps the entire NFA 1934 would have been overturned.
The Miller decision still establishes that military weapons (so called "assault weapons" and 30-round magazines) are the most constitutionally protected. I'm not sure the current Supreme Court is honest enough to rule that way. On the bright side, they tend to hold their previous decisions in VERY high regard (perhaps higher than the Constitution itself)
"The only way to stop a bad guy with a gun is with a good guy with a gun"