It boggles the mind that anyone would consider the sporting use idea or the militia idea.
All the amendments are about guaranteed individual rights; free exercise of speech/religion, protection against government intrusion and property seizure, etc. And yet some think people risked their lives to break from Britain and thought hunting was the second most important thing behind being able to say what you thought and worship the way you believed? Even sillier is the idea that there needed to be an amendment that recognized a government’s right to form an army?
No wonder people vote the way they vote.
I don't reckon it'll be too much of a boggle for you to find out from just which law that*sporting use idea* was copied:
The framers of GCA 68 borrowed an idea -- that certain firearms are "hunting weapons" -- from the Nazi Weapons Law (Section 21 and Section 32 of the Regulations, page 61 and page 73, respectively, of "Gun Control": Gateway to Tyranny). The equivalent U.S. term, "sporting purpose," was used to classify firearms. But it was not defined anywhere in GCA 68. Thus, bureaucrats were empowered to ban whole classes of firearms. They have, in fact, done so. -- "Gun Controls" Nazi Connection by Jews for the Preservation of Firearms Ownership.