User blog comment:Derp2000/Tips on Crucible/@comment-25175520-20150311165021/@comment-66.37.64.58-20150311191015

you could call impact sort of a damage per shot, it is inversely proportional to the rate of fire, if one is high the other is low and vice versa. In my opinion, I really prefer low RoF and high impact weapons due to low kill times.