good lord, this is the game I've been waiting my whole life to play. Akimbo Rangers are the most fun you will EVER have shooting someone in the face. Four barrels of hot death, and the kill shots are so much more satisfying than any other gun, imo. The first time you blast someone OFF THE ROOF on Highrise, you will fall in love.

Seriously, fuck around part-time with the Ranger for 3 or 4 matches to unlock Akimbo, then load up

(whatever primary weapon, either an AR for range or a riot shield for fun)
Akimbo Rangers

Marathon
Cold Blooded
Steady Aim

The VERY first match I tried this, I went 26-8 on Estate, which is NOT a map conducive to shotgunning. Cold blooded assures they never see you coming, Marathon assures you get there quick, and the two double-barreled shotguns assure that you tear them apart when you get there. The range is better than you'd think, and you have 4 lightning-fast shots, each of which is almost always a 1-shot kill.

I cannot recommend this highly enough if you're a run-and-gun type player.