I have heard some people suggest that being armed is not a civil right. That our Constitution does not give ordinary citizens the right to have weapons.
Actually, it is a right whose protection from government interference is a civil liberty. To me this makes it a civil right, although civil rights usually refers to the equality of liberty for all citizens.
Merriam-Webster defines civil liberty as:
Freedom from arbitrary governmental interference (as with the right of free speech) specifically by denial of governmental power and in the United States especially as guaranteed by the Bill of Rights —usually used in plural 
So a civil liberty is freedom from governmental interference with a right. As in “the right of the people to keep and bear arms shall not be infringed”.
Where does this right come from?
When people say the Constitution doesn’t grant people the right to be armed, that is correct in a sense: it just forbids the government from infringing that right. Which means it was an existing right before the Constitution was written. Throughout recorded history, if not longer, the right to own and carry a weapon has been a key aspect of being a free person.
In ancient Greece, owning weapons was a primary distinction of citizenship  — slaves could be issued weapons to fight in armies, but they could not own them.
Roman citizens also had the right to own weapons, unlike slaves. Gladiators, like Greek slave-soldiers, did not own their weapons. (Slaves with weapons led to revolts such as the one led by Spartacus in 73 bce.) When a gladiator was granted his freedom, the very symbol of this act was the presentation of a replica weapon, the rudis. 
Developments in Britain from around the 11th century onward, and spanning the transition from sword to firearm, culminated in the English Bill of Rights (1689). This document codified for the first time the right of individual subjects to be armed for their own defense. 
So by the late 1700s, there was already a long-standing right for free men to bear arms. And when a group of British subjects declared themselves instead to be American citizens, this is one of the rights they chose to enumerate and preserve.
More recently the US Supreme Court has affirmed that the Constitution does in fact preserve an individual right to be armed. And that this right is not limited to muskets, nor extended to nuclear weapons, but refers to weapons currently typical for a milita (e.g. pistols and rifles). 
The bottom line
Guns have been with us for over 500 years; the right of free men to possess and use weapons since long before that. The civil liberties provided by our Constitution include the protection of that right.
I call that a civil right.
- Merriam-Webster online
- Metropolitan Museum of Art
- Harper’s Dictionary of Classical Antiquities (At Tufts University)
- JonathanTurley.com (ABA award winning blog)
- JonathanTurley.com (this time on McDonald and on Heller)