All guns are made for killing. It doesnt matter if its a .22lr, .45acp, or 7.62x54r. There isnt a purpose for guns except killing and practicing to kill. Self defense does not make killing any better or worse. I guess you could be scared of the capacity, but depending on the state, that AR could have less capacity and be significantly slower to reload than a standard handgun. I just dont understand what specifically makes you think a bigger gun is more dangerous than a little gun. If youre okay with gun a, why not gun b?