canyon.But you must hold that alignment before,during,and after the shot.The same is true for bead -sightedguns,albeit with somewhat reduced accuracy potential. The realities of requiring a shot at the length of a football field are slim for anyone who has properly studied his "opponent" (i.e., select a rifle to solve likely rifle problem), but you do not want to limit your capabilities in the event that your studies were not complete.In such cases, the availability of slugs and an understanding of supported shooting positions will allow you to reach out and...well,you know.