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.I have no idea why so many people try to invalidate the Second Amendment by harping on the "militia" part.
The Bill of Rights, like the rest of the Constitution, is written in eighteenth-century English, which reads a bit archaic to modern speakers, but the rules of sentence composition have not changed much since then.
The first half of the Second Amendment ("A well-regulated militia...") is prefatory language and has no bearing on the meaning of the main statement ("...the right of the people to keep and bear arms shall not be infringed.") It makes no sense, logically or linguistically, to argue that only militias have the right to keep and bear arms. In more "modern" English, the sentence would begin:
"Because a well-regulated militia is necessary for the security of a free State..."
Another example on the structure of the sentence comes to us from the expanses of the Interwebs. (I don't know who came up with this, but it's 100% on the money.)
"A well-crafted pepperoni pizza, being necessary to the preservation of a diverse menu, the right of the people to keep and cook tomatoes, shall not be infringed."
This sentence has exactly the same structure as the Second Amendment. Try to argue from it that only pizzas have the right to keep and cook tomatoes, and only well-crafted pizzas at that.
Of course, the whole linguistic argument should not be necessary. The Bill of Rights is a restriction on the government, not on the citizens. It's not a list of things allowed to citizens, but a list of things most definitely not allowed to government. (The rest of the Constitution lists all the things the government may do, and that list is inclusive--meaning that if it's not in there, the government may not do it.)