The amendments to the original arms amendment in the bill of rights - originally the fifth, now the second - are instructive. They seem to show that the original version of the article made claims that contemporaries thought were arguable.
"A well regulated militia, composed of the body of the People, being the best security of a free State, the right of the People to keep and bear arms, shall not be infringed, but no one religiously scrupulous of bearing arms, shall be compelled to render military service in person."
Removed:
1. "composed of the body of the People" ie the composition of the militia was originally thought to compose the body of the people but as the amendment was discussed, they changed their mind.
2. "but no one religiously scrupulous of bearing arms, shall be compelled to render military service in person." ie there's a right to bear arms and a right not to bear them.
Edited:
"being the best security of a free State" became "being necessary to the security of a free State". ie they weren't certain such a militia was the best security available for all time. and of course now we may reasonably argue over a militia's necessity for security at all.