What hand cannon are you using? I get one shot kills on level 30 mobs with my hand cannons.
And the damage is not pretty much the same as Scout rifles. Hand cannons deal much greater damage. Especially if you are using them correctly. A hand cannon is a skill weapon where you should be getting (or trying to get) only head shots. Often times with my Hawkmoon I fire off my 13 rounds and that equals 13 kills (unless majors or ultras were involved). If you are consistently getting body shots with a hand cannon you are using them wrong.
EDIT: whoa, just noticed the date of this post. How did it end up at the top of my feed? lol