Yes, Donald Trump misspoke about the 2nd amendment. I believe that when he mentioned that there was something his supporters could do to prevent Hillary Clinton from appointing a Supreme Court Justice that would vote to reduce citizen's right to bear arms and did so by referencing the second amendment he did so purposefully and with clear knowledge of what he was insinuating. Donald Trump's supporters value him as a candidate for his willingness to speak his mind without hiding behind political correctness. In this case his lack of tact and poor decision making was clearly displayed.
Donald Trump misspoke about the Second Amendment when he said Hillary Clinton would abolish it. She has never uttered this phrase. While she supports gun control laws, this is far different than completely abolishing the Second Amendment. This is just a way for Trump to rally conservative support since he has supported gun control in the past.
He did not misspeak, in fact, the media is going insane in trying to spin his quote into an actual threat. People would not better to calm down and make their own assessments. They really need to be careful in not putting words in people's mouth. That can get them lawsuits.
No, what Trump said about the 2nd amendment was something he meant to say. Trump doesn't misspeak. He says what he means. He says stupid things constantly and now people are surprised that he said something that could spark violence. He has instigated violence at rallies before. He was serious about what he said. The only reason he and his aides are trying to backtrack is because of the backlash, not because he didn't mean it.