ok first you have too have a shot-gun or gernade laucher attchment. now start a mission(anyone).waste all of your ammo.now go around and kill someone that has a primary weapon out. now switch to your attchment and pick up the gun.pick up your primary and as you can see, that you should have anumber with a neg sigh like this "-30". theres no use for it, its just somthing i found messing around
