I'd love to read more good discussion of this question, but there've been several good answers on the subject here before, such as this explanation of the historical context by /u/uncovered-history and this explanation of the Amendment's legal history by /u/Georgy_K_Zhukov.
I tried to explain the historical context of the Second Amendment as best I could in that answer that /u/Evan_Th was kind enough to link to. I mention the purpose as well, but not as directly as your question perhaps would like it to be. So I'll expand on it just a little.
One counter argument I've seen popping up, mostly citing or plagiarizing Scalia's argument in the infamous District of Columbia v. Heller case from 11 years ago. In his decision, he wrote that the idea of the Second Ammenemnt was all about protecting people's ability to own whatever weapons they needed, known as the "common use argument. He wrote “The right to keep and bear arms, is defined not by what the militia needs, but by what private citizens commonly possess.” However, this is not what historians of this period agree with.
Well-respected legal historian Saul Cornell wrote extensively on this. His book A Well-Regulated Militia: The Founding Fathers and the Origins of Gun Control in America is widely respected by a wide variety of historians, regardless of personal political biases. He also wrote an article for the Atlantic a few years ago, that summarized points in his book, and said:
The larger problem with a market-driven theory of gun policy is that it is the opposite of the Founders’ intent as well as the plain meaning of the text. The Second Amendment was not designed to hobble government regulation. At the time, men arrived for military service already armed with guns the government required them to purchase. Contrary to Thomas and Scalia, the law did not countenance Americans simply showing up with whatever weapons they owned—that is, what was in common use. Without specific regulations and instead following common use or preference, most Americans would likely have shown up for active duty with fowling pieces, which were more like shot guns than muskets, because these were better suited for putting food on the table. In other words, the Founders recognized that if left to the free market and people’s own preferences, America’s militias would be prepared to hunt turkeys, not fight a powerful European standing army. A reliance on the market could have cost America its freedom. The various militia regulations enacted by states in the colonial period and after the adoption of the Second Amendment specified what weapons were required to meet the legal obligation of citizens to serve in the militia. Failing to report to the militia properly armed with the right weapon could result in fines. If the Founders had understood the Second Amendment in the way Scalia and Thomas suggest, the United States would likely have lost the American Revolution.
Please let me know if this helps clarify my answer in reference to your question. As always, I welcome any follow ups!
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Thanks everyone.