User blog comment:Duskeh/Did anyone ever figure this out?/@comment-11188061-20131031014124

There are two things. Though note that this is just a theory, nothing has been confirmed yet.

One would be that the Cross Bullets are NOT the reason why Ruby went super speed. That's just her Semblance.

Two would be that the Cross Bullets gave her attacks the ability to 'Scatter' her enemies.