Is there any evidence that the Second Amendment was not written to give any and all free persons the right to make, purchase, or otherwise acquire without theft, any and all such artifacts as might be useful as weapons in a well-functioning citizen army, without interference from the government?
Slaves are not free persons. Prisoners are not free persons. Unemancipated minors are not free persons (they are wards of their parents, and have such freedoms as their parents choose to give them). Committed inmates in lunatic assylums are not free persons. Outlaws are not free persons (since they are subject to capture at any time).
If it is no longer acceptable to give all free persons the right to acquire without restriction any and all such artifacts as could be used as arms in a well-functioning citizen army, then the Constitution should be amended to change that. I would expect that an amendment allowing Congress to restrict private ownership of significant quantities of fissionable materials, for example, could be ratified without too much difficulty if courts held that such an amendment would be required to impose such restrictions. So what's the problem with regarding the Second Amendment as applying absolutely to all free persons?
It's an irrelevant point. The government's duty is to protect the rights of its citizens, to provide for the common defense, and to ensure a safe and secure environment in which society can freely prosper. To permit what you describe would be to fail in that duty. This well-functioning citizen army would crumble into hundreds if not thousands of mini-groups, all vying for power, just as one sees in Iraq today. You would have Hispanic, Black national, Asian, White Christian, and numerous others battling each other and the government at the same time. The government has a duty to ensure that never happens. So the 2d Amendment, just as the 1st and 14th, are reasonably regulated to protect the rights of the people and guarantee a safe and secure society.
If it is no longer acceptable to give all free persons the right to acquire without restriction any and all such artifacts as could be used as arms in a well-functioning citizen army, then the Constitution should be amended to change that.
I disagree. No part of the Constitution was written to knowingly provide a means of effectively overthrowing the government it created. If the guarantee of equal protection of the law prevents all discrimination, then gay marriages could not be prevented, as they have in many states. Reasonable interpretation of the 14th by the courts however have found that if a state can articulate a compelling interest in the discrimination, it will be permitted. The same goes for restrictions on free speech, and will certainly be the case for the 2d Amendment.
I would expect that an amendment allowing Congress to restrict private ownership of significant quantities of fissionable materials, for example, could be ratified without too much difficulty if courts held that such an amendment would be required to impose such restrictions.
See my earlier explanation. If this country failed to restrict fissionable materials to "groups" of free people, it would have no basis for existence. The same logic holds for most other types of military weaponry. No court is going to find such restrictions unconstitutional, therefore no amendment is needed to clarify the obvious.