The disadvantage lies in the fact that the barrels of a double-barreled shotgun, whether "O/U" or "S×S", are not parallel, but slightly angled, so that shots from the barrels converge, usually at "40 yards out". For the "S×S" configuration, the shotstring continues on its path to the opposite side of the rib after the converging point; for example, the left barrel's discharge travels on the left of the rib till it hits dead center at 40 yards out, after that, the discharge continues on to the right. In the "O/U" configuration with a parallel rib, both barrels' discharges will keep to the dead center, but the discharge from the "under" barrel will shoot higher than the discharge from the "over" barrel after 40 yards. Thus, double-barreled shotguns are accurate only at practical shotgun ranges, though the range of their ammunition easily exceeds four to six times that distance.