Scope
A magnifying optic mounted on a rifle for medium-to-long-range shooting.
Also: riflescope, telescopic sight
A scope is a tube-shaped magnifying sight with a reticle, used for precise aiming at distance. Scopes are specified by magnification × objective lens — a 4-16x50 scope variable-magnifies between 4× and 16× and has a 50mm objective. First-focal-plane (FFP) reticles scale with magnification; second-focal-plane (SFP) reticles stay constant. Scopes typically mount via Picatinny rings or proprietary bases, often on a drilled and tapped receiver.