If you are running low on ammo, anytime you see a firearm laying on the ground walk over top of it. You will pick up the clip. The other Ghosts will also do this automatically if they walk over a firearm that is the same as what they are equipped with.
When carrying a large automatic weapon, the controls will feel sluggish because of the weight of the gun. However, if you switch to a hand held gun, the controls will be more responsive.
