Some random rivet tips, when using steel rivets in aluminum, use Alumelast paste, it's a corrosion reducer that helps with the disimilar metals, and when using something to extend the rivet away from the nose of the gun (nut or stop sleeve) don't over do it, if you don't leave enough mandrel (the pin part of the rivet) in the gun it will break the tips off the jaws inside the gun that grip the mandrel.