For assault rifles, the scope's size and functions are similar to an ACOG Scope, more specifically, the Modern Warfare 2 version. However, the increase in zoom is less than that of an ACOG, though still noticeably more than iron sights. For semiautomatic or bolt-action rifles, the scope is as large as a full sized sniper scope, with the same zoom and reticle as well, practically converting them into sniper rifles but more effective, as the M1891/59 has more power with the same rate of fire, and the M14 less power, but much higher rate of fire, less recoil and has the same hipfire accuracy, allowing for much better CQC engagements.
The Scope returns in Call of Duty: Modern Warfare 3: Defiance, this time more frequent. Certain weapons that are scoped are used frequently than other scoped weapons respectively, e.g. the scoped AK-47 is seen more frequently than the AUG A3. Also, enemies in the campaign that are using the scoped AK-47 always seem to go for headshots, no matter what range.