If "arms" at the time of the Founding Fathers meant the absolute most deadly, harmful, dangerous weapon(s) in the world (cannons, muskets, flint lock pistols, swords, etc), it serves to reason that they wanted to guarantee that the ability of the citizens to have equal arms as the governments of the world (since that is exactly what they did) when they wrote the 2nd Amendment. It would be equivalent to permitting nuclear weapons if we were writing the Bill of Rights in today's time, since they are arms, you know nuclear arms, and it says my right to bear them shall not be infringed. Could they have imagined nuclear weapons and the other advances in weaponry that have happened? No, but that doesn't negate the original intention and principal of the document. I'm aware that we have a super dope ass kicking military but they're not exactly being used to protect us lately, let alone that should have nothing to do with me being able to protect myself. Furthermore, based on some excerpts from the Founding Fathers and Article 1 Section 8, I don't think they wanted us to have a standing army in times of peace. Which is why they wanted the people to be armed, to defend themselves if need be from whomever it may be. I'm not saying I know what people were thinking 200+ years ago, it is just my hypothesis. I find it interesting that a lot of things that are contentious now and highly debated are things that the Founding Fathers never implemented when they had the chance. Things like the draft, things income tax, things like making sure the Government was better armed than its citizens, things like redistributing wealth to those who were not doing well (be that because of a bad choice they made or being disabled by no choice of their own). They relied on charity and family and friends to care for people and on the country to be able to come together and fight when they're common values and their geography was threatened. They relied on people to care for themselves for the most part. It is quite possible that times have just changed and that society no longer values the same things, or perhaps they are so disconnected from how things were that they don't think of alternatives.