User blog comment:Plexioth- xD/Monster Hunter 3 Ultimate/@comment-76.114.237.96-20121116012229/@comment-112.209.18.3-20121116174142

If they haven't changed much from MHP3rd... all Heavy Bowguns can have different attachments like shields (really weak autoguard), scopes (increase first person aim zoom), and power barrels (increase attack). Unfortunately, you can't have a shield and a power barrel at the same time. And the roll is the default dodge move for an unsheathed Heavy Bowgun user.