Aim Assist pops your crosshairs to an enemy whenever you press the ADS button. By default, this is turned “on” in the campaign. There’s an important setting available in the game’s settings menu. Some weapons, like the sniper rifle, are almost impossible to use effectively with hipfire. Weapons are less accurate, and will less reliably hit an enemy in this mode.
Target of Opportunity: Operation Taken Dagger Single-Player > Campaign Walkthrough: Rising Threat Single-Player > Campaign Boot Camp: For First-Time Players Call of Duty 4: Modern Warfare Multiplayer.