" what is wrong with someone firing back at any mass shooter? "

Well, when that congresswoman (and several others) was shot in Arizona a few years ago, one young man in the crowd had a gun, and was about to return fire when he realized he had mis-identified who was guilty.

If many people... say, a majority- like the NRA would like to see... carried guns, and a terrorist or crazy nut started shooting, would YOU like to be in the crowd when several... or several dozen 'concerned vigilantes' started shooting? Most people who DO carry guns have no experience in sudden emergency situations.... they 'may' know how to aim and shoot, but that is far from being competent to judge WHO to shoot at, and where innocent bystanders are.

Most terrorist or crazy person attacks come with no warning! Even dedicated 'defenders of the 2nd amendment' cannot be counted on to be in the right place and able to make the right choices under high-stress situations.
(This is different from a liquor store clerk possibly being able to stop a robbery... but even that has more sad than happy stories.)


And remember.... everyone who has NOT been judged to be crazy or a felon can currently buy guns until they DO cause a problem.... and then it's too late. This is how most of the recent major shooting have gone down.