The Right to Bear Arms

The actual main reason the U.S. has "The right to Bear Arms" when other nations don't is because this is the way our nation has always defended itself from the Revolutionary War to Andrew Jackson driving the British out of New Orleans and even to the Civil War. An Armed electorate is how we actually remain free with a literal civilian militia always there intact.

Any nation that would even think about attacking the U.S. would have to consider a Guerrila war for 50 to 100 years with an armed electorate much like during the Revolutionary war. We are maybe one of the last nations on earth that allows its citizens to be armed even with hunting rifles.

Changing gun laws will not solve the problem of what happened today. Remember the gunman today didn't own ANY weapons and likely couldn't have bought weapons because of his mental illness. He took his mother's weapons and used them to kill his mother, the other teachers and all the kids in his mother's classroom. 

The problem is not about registering weapons because he would have gotten them anyway. The problem is his mental illness. Understanding that these types of shootings are ALWAYS about someones temporary or permanent mental illness. And if you think about it there really is no way to keep weapons out of the hands of people like this. If you take weapons away from law abiding  people they won't be able to defend themselves from criminals who break into their homes to rape them and kill them and their children. If you take weapons away from law abiding people then only criminals will have them and then crime will really increase because criminals will know there won't be any serious resistance from law abiding citizens.