This is extreme important in understanding the context of the Constitution. First thing I want to point out is that the 2nd amendment refers to the right to "keep and bear arms". "Arms" is broader than and inclusive of "firearms". That means that guns, firearms, are just one type of arms or weapons that people are understood to have the right to have.
Arms also includes blades, spears, bow and arrow, etc... These are all weapons, or arms, that are readily and universally identified. So the Second Amendment shouldn't be construed as limited to guns.
Let's get back to identifying context again. If the Constitution is based on recognizing natural or God given rights, how does that relate to arms? Because the Right to Life MUST include the means to defend it and sustain it. The natural or God given Right to Liberty MUST include the ability and means to defend it and maintain it.
Arms are a, if not THE, primary means to accomplish those things. To deny the means, tools and know-how to defend and sustain/maintain our God given Rights is to deny that we have those natural or God given Rights to begin with.
So, the Second Amendment says;
For those not understanding the nature of contractual writing, and the Constitution IS a contract, this says that
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.
"Because we need people to be ready and able to fight for their Right to live in freedom, to be able to defend that freedom, we want to make sure people have the means to do that and nobody will get in the way."
Because we have been told by the authors of the Constitution in their own words (see the Federalist Papers as just one example as well as the personal journals and letters of those people who go into much greater detail) the Militia referred to are the people themselves. There is no greater fighting force on Earth than one who is armed and ready behind every door. The Emperor of Japan figured this out the hard way.
Now, again, using the context which is provided by both the Declaration of Independence and by the framers, this is not exclusive to firearms thus it is not delimited to specific types of firearms. That would be ridiculously out of context.
As many have pointed out, arms are no more defined and delimited by the Second Amendment than the means of communication are by the First Amendment. The example of guns being limited to the technology of the time would then mean computers and advanced printing technology, 3D printers for example, would be unusable by the citizenry as well.
Remember people, the founding documents are founded on individual rights. Each individual has the God given rights to life, liberty and pursuit of happiness, among others. Each individual thus has the correlating responsibilities for exercising those Rights.
To put it short and sweet, "Do what you want as long as you don't get any on me." The responsibility we have pertaining to having and exercising our God given Rights is to do no harm to the next individual.
Rights do not come without responsibility. It is NOT the government's place in this country to grant us our Rights nor is it the government's place to dictate or deny our responsibilities.
I will end this the way it began.
"The Rights we refer to in the Constitution and consequently the Bill of Rights are not granted by the government. These are Natural or God given rights that the founding documents recognize as inherent."