One of my history professors pointed out that the right to bear arms was never meant to be used in the context used today. It specifically meant the right to pick up arms and use them inside your right to form a militia. It as well as many other rights stated were in direct response to the british rule and the tactics we used in the revolution. Designed so that the American populace had the right to take up arms, form a militia and overthrow a gov't that is no longer servicing it's populace and/or has grown oppressive.
Freedom of religion, right to free speech, not having to give quarter, freedom of assembly, etc. all are rights written in response to british rule, and so is the freedom to bear arm.
That said, it's meaning has evolved over the ages to mean in todays society the right to own a gun.
But that was far from it's intent. For the colonist of that time, owning a gun was never in question. It was not something you needed to guarantee or permit, it just was. It was an everyday tool like a hammer. Needed often times to catch ones dinner in many areas, protection from "savages" and criminals. To them putting a clause to ensure you could own a gun was as trivial as putting a clause in to own a hammer. It was written to protect our right as citizens to bear those arms (which meant all weapons one might use) as part of a militia in protection of our rights and liberties.
It is only since firearms began to require permits in order to own and our universally seen right to own a gun started to come into question, that interpretation of that right shifted to the right to own guns.