Before making a ranged attack, you may take a full-round action to line up your shot. This grants you a +2 circumstance bonus on your next attack roll. Once you begin aiming, you cannot move, even to take a 5-feet step, until after you make your next attack, or the benefit of the feat is lost. Likewise, if something disrupts your concentration or someone attacks you before your next action, you lose the benefit of aiming. You may continue aiming after the first round. For each full-round action you spend lining up your shot, the bonus increases by +2 to a maximum of +6.