Well I am finally the highest rank possible in zombies. Got my double shotguns and blue eyes on now, all it took was relentless play, and 46,000 kills, multiple 40 round games (5 give or take), multiple 30 round games (20 give or take), and even more 20 round games. Also about 6,000 grenade kills, 10,000 headshots, and almost 70,000 Gibs.
I saw a guy that had 25k kills have the double shotguns, and I was pissed. Played a game with him and all he did was glitch in the power station, and then eventually he died and rage quit... So of course the round 28 that I made it to 4 player didn't count.