Bias
An article biased against guns would show only facts and information that support the author's position.  They would list suicides, accidental shootings and other facts showing guns in a negative way.  An article biased for guns should show only information that supports the author's position.  The positively biased article would discuss 'lives saved' by guns, numbers of crimes prevented by civilian gun use, and other facts and data that put gun ownership and guns in a good light.