Secondary Weapon: None
Lethal: Fragmentation Grenade
Tactical: Concussion Grenade (x2)
This loadout is designed primarily for objective-based missions. It won't serve you too well in free-for-all matches or a straight-up deathmatch, but when you've got groups of enemies clustered around a flag or a capture point, it's going to mess up their plans considerably.
The S12 Shotgun is a fantastic boomstick that can be unlocked early in the game, get this thing close to someone's face and you'll be making brain jello in no time. The combination of the Lightweight and Extreme Conditioning perks will keep you nimble on the battlefield while the Quickdraw Handle attachment and Dexterity perk let you jump into action faster than your more tactical enemies.
There's no doubt this is a class for the berzerker at heart, but if you want to play it a little tactically, make use of the Concussion Grenades to stun enemies before diving in. Toughness will help mitigate any of the few lucky bullets that manage to clip you while they're in a fog while you dance around making organ stew out of your foes.
Be careful to keep on the move though; at distance you're pretty much screwed with this set. Either close the gap gracefully by ducking between cover as you approach your opponents, or if you notice they've spotted you just turn and run. It's better to flee and live so you can flank them on the other side than charge in and face certain death.