I'm currently trying a 2h gun, with 1.60 fire rate, and I'm finding it's knockback to be extremely effective. In fact it's too effective and should be nerfed. I can just stand there and shoot an enemy far away, bullet knocks it back and by the time it's back at the location where it was knocked away from the first time a second bullet hits it and knocks it back again. I can just repeat this until it's dead without making any effort at all to kill it. I suggest tuning down the knockback effect on ranged weapons a little...or a lot