(adsbygoogle = window.adsbygoogle || []).push({}); I tried this and it work all though it took me a week i dont really have that much time but heres how i got the shotguns.
Ok so what i did was ill play a few games on town survival not custom solo only, with around 700+ kills and about 2 downs then after about 3-5 games play survival on farm then tranzit and if you want to throw in 2 games of grief then nuketown if you have it if not substitute it with bus depot. Make shure that your headshots are around 1/3 of your kills my final k/d was 287 and the highest round that i ever made it to was 35 so thats what i did try it out let me know thatks.

works for me

How long did it take you?

The maps has noting to do with it, I got the shotguns and I only play on Town and Tranzit.