VENTILATED RIB

A raised sighting surface which is separated from the barrel by means of posts that allow air to circulate around it. Its purpose is to minimize heat waves in the line of sight. Also called Bridge Rib.

VERNIER SIGHT

A long-range sight with a mechanism for adjusting windage and/or elevation settings as read on a short scale in conjunction with graduations on a longer, linearly calibrated, scale.