It seems a lot of people have a misconception of the meaning of the Second Amendment; The Bill of Rights gives no one anything. What it does do is stop the government from infringing on your right that is inherent to you just being a person. This goes way back 200 years in British common law.
As for getting the soldiers and National Guard on our streets to make them safe. Can’t do that because of Posse Comitatus. It makes it illegal for federal troops to be used as a police force. If you don’t think this is a problem, check on the fiasco of the aftermath of the Boston bombing where the police dressed like the military went door to door without warrants. If you didn’t want to comply, the police broke into your house and searched it anyway.
There are estimated between 5 million and 10 million AR-15s in America. As of this writing, there have been 20 AR-15s used by school shooters. That is 0.0002 percent of AR-15s. You are worried about this? This is going to sound heartless but your child is more likely to be hit by lightning than be killed by a school shooter. It isn’t callous, it is just math.
If you really want to understand the Second Amendment, read “The Federalist Papers” written by the real writers of the Constitution — James Madison, Alexander Hamilton and John Jay — in particular numbers 29 and 36.