A Well Regulated Militia

SCOTUS blog reports:

Analysis: 2d Amendment extension likely
McDonald v. Chicago, 08-1521, Argument recap

Lyle Denniston | Tuesday, March 2nd, 2010 11:26 am

Analysis

The Supreme Court on Tuesday seemed poised to require state and local governments to obey the Second Amendment guarantee of a personal right to a gun, but with perhaps considerable authority to regulate that right. . . .

"A well regulated militia, being necessary to the security of a free state, the right of the people to keep and bear arms, shall not be infringed."

Well, that's the Second Amendment to the Constitution of the United States, though there are some alternate versions, with different punctuation.

I don't understand how the far-right, strict constructionist, textualist, original-meaning justices can fix the Second Amendment in the late 18th century as a way of permitting citizens to arm themselves with hi-tech 21st century firearms. How does that work? Why aren't those rights, if they actually exist, limited to 18th-century arms?

Just asking.