Well, as someone who is actively trying to finish the feat, which I check after almost every match (even looking to heat map here on the forum stats), I have never gotten a close kill to register while I was ADS. Some of the close hip fires don't register either, but I think that is more to do with when the kill registers.
All shotguns need red dot sights so they can do awesome pro shotgun sniping kills.
/sarcasm
I wouldn't bother. Use perpetrator ammo and shoot form the hips. It works just fine.
Yay!!!!! I use it on my Jackhammer it rlly helps with my accuracy and helps me get crazy kills!!!