My recommendation, you need to get 1 or 2 big games. Either do Die Rise or MOTD solo, put up a 70+ with 10K+ kills in one game.

That got it for a few of my friends that were stuck with good stats

What is your average rounds per down? What I have noticed is rounds per down to get shotguns. Some dude i saw sat in a glitch with other people when they got to round 100 he got shotguns and he had 0 KILLS that game! What does that prove? Thats its not about kills it must be about rounds and downs. Try to get 1 or 2 downs per game at the most. btw quiting games does not affect your rank unless you quit on a low rounds. i have quit a ton of games at high rounds and never lost my shotguns.