Now that I think about it, I recently had my friend (Who prefers paintball and Nerf, whom I had to drag to the airsoft store) play Call of Duty 4. Now all he'd ever use is a grenade launcher.
So if I had to guess his loadout.
It'd be using the CAW revolver grenade launcher (akimbo, naturally)
With another Caw revolver grenade launcher sidearm.
And 2 claymores.
And Juggernaut and Martyrdom.