I guess I can now confirm 170 kills per down ratio does NOT give you the shotguns rank. Does anyone actually know how you get it? Frustrated because I played a bunch of solo games to increase my ranking quicker but it still took quite a while as I originally would play the bus station level when I wanted to play for 20-30minutes vs the 3hr+ games that can happen in town.
One thing I will point out is my headshot ratio is not particularly good as I typically use only the knuckles up until 14/15. I guess I will start playing headshots only, I'm beginning to think the shotguns is impossible.