Long time back there was an article in one of the gun magzines about the Hornaday Light Magnum ammuntion. As I recall the author stated that it was a compressed load(270 Win??). He pulled the bullet and dumped the powder out. Then he tried to put the powder back into the case. He was unable to accomplish the task. I would say that is a compressed load.
He stated the factory used special equipment to load the Light Magnum ammunition.