The first thing you have to do is start the game on forge world in forge.

Then when you're in the game you have to drop your weapon by getting a hologram and any turret.

Now set your controls to recon and pick up the hologram. Then detach the turret and start walking backwards and press "RB" and "B". It may take a few gos.

Once you have dropped your gun get away from it, because if you walk into it you will pick it up so the best thing to do is to go to anther island or up to the hanger.

Then buy a warthog and go over to the side were it says "hold B to ride in warthog" and you should sit down for a second or two.

After that you should stand up and the warthog is still in operation and you will still have no gun.