Any weapon's "reasonableness" for use is dependent on potential threat to innocent bystanders. In a perfect world that respected our right to arms and self defense we would have a right to any weapon we want BUT we could be charged with "reckless endangerment" for actions that put our neighbors at undue risk.
By this standard, a full-auto .22LR home defense gun makes more sense than a 5-shot 50BMG in a typical suburban tract house situation. The 50 (unless loaded with frangible ammo that comes apart into dust or BBs at the first thing it hits) will go through a dozen or more homes and would make a psycho home defense gun. The 22s on the other hand will be stopped or radically slowed by most home exteriors so even if you spray 150 out per mag, who cares as long as the target was a valid threat and you greased him good?
If on the other hand you're running a cargo ship across the South China Seas or off the coast of Somalia and you're worried about pirates, multiple turret-mounted full-auto 50BMGs make perfect sense...along with high explosives, incendiaries, 20mm or bigger cannons, what have you.
200 years from now, you've got a nice little asteroid mining homestead, your nearest neighbor is 800,000 miles away and you set up a nuke-based home defense system for space pirates, kewl, not a problem.
This "bystander threat level based standard" makes MUCH more sense than arbitrary limits on full auto, caliber, explosives, etc.
Andrew S:
There is strong supporting evidence that the purpose of the 14th Amendment (1868) was to ensure that the entire "privileges and immunities of US citizenship" were applied to the newly freed black population - and that phrase had been found by the US Supreme Court in 1856 to mean basically "the entire Bill Of Rights plus the traditional rights of free Englishman such as the right to travel"...and specifically including the 2nd Amendment right to arms.
If this interpretation is correct, it means three things:
1) Since blacks didn't yet have the vote (that was the 15th Amendment of 1872) then the right to arms was being decoupled from the "political right" of militia duty which in 1792 was very similar to the right to jury duty. In other words, blacks in 1868 were declared to have "civil rights" but not "political rights" (yet) the same as a free white woman would have had at the time. The right to arms was being transformed from a political right to group and community self defense (for any purpose up to and including standing up against a crooked/tyrannical government) to a personal right to self defense.
Multiple quotes from the key author of the 14th (John Bingham) support this view. See also the books "That Every Man Be Armed" (1984) by law professor Stephen Halbrook of George Mason or "The Bill Of Rights" (1998) by Akhil Reed Amar of Yale, two people with wildly different political stances who independently came across the same Bingham quotes. Halbrook is a lawyer for the NRA when he's not teaching law but Amar is well known in Liberal circles and clearly didn't LIKE what he was writing.
2) If Amar and Halbrook are correct, then it's not the guns of 1792 we should be looking at as "standard models of possible weapons". It's the guns of 1868. And that's a whole 'nuther kettle of fish. The Gatling Gun was invented in 1862 and fielded by 1863/64. The Mormons had invented the snubnose big-bore defensive revolver meant for concealment by 1858 or so (look up the "Avenging Angels"). Entire Northern Regiments had been equipped with 15-shot lever-action rifles and by 1868 these were firmly in civilian hands. And everybody knew S&W's patent on the through-bore revolver cylinder was going to run out by 1872 (eagerly awaited) and were starting to at least think about what cool new bangtoys would result...some of the designs that DID result are still available in practically every gun shop in America, esp. the Colt SAA and derivatives...and are still highly effective weapons even in the original caliber with period-reproduction ammo.
3) Finally, if the goal was to arm blacks against the rising tide of KKK (and there was a lot of Federal legislation to do just that between 1866 and 1870), then the framers of the 14th would have known that open carry of personal defensive handguns would have gotten Southern blacks shot on sight. Only *concealed* carry would have been effective for defense against crooked sheriffs, the KKK and the like.
The Second Amendment in it's original "militia format" may be a bit dated, although not completely dead. But in the "personal defense format" of the 14th Amendment, it's VERY much alive and kicking.