This little beauty affects all non-automatic rifles, including rifles (der ), shotguns, and sniper rifles. So pretty much, one perk - that you can take with very little PER - gives you awesomeness in close ranges, mid ranges, and even far ranges. I love it, but at the same time, I feel it's a bit OP.
And I get it...it's a single player game...balance doesn't matter too much...but still, I would have loved to have seen a Shotgun Surgeon perk add to the END tree to give shotguns their own behavior.