Perimeter Prism Check

A spent brass key lay half-hidden beneath the curtain fold on the sill ledge. I approached in three measured paces. Structural mass verified solid. Bracing my left boot against the frame, I hauled the notched stem upright and tilted it sixty degrees against the glass pane. The midday beam struck the brass cutouts, casting sharp angled shadow bars across the white paint. I positioned my rifle butt against the base to prevent recoil. Line of sight confirmed.