Iron sights are vital for killing an enemy at long range, as "hip firing" is inaccurate at anything beyond close range. Conversely, at very close range, aiming down the sights can be impractical, as in the time it takes to bring up the sights, hip-firing could have already taken out the enemy and denied them the ability to fire back.
While aiming down the sights (ADS), a player's shots become much more accurate than while hip firing. However, while ADS, the player's walking and turning speed is slowed, meaning that moving in ADS is much slower than moving while not aiming.
Modern Combat: Sandstorm
In Modern Combat: Sandstorm, weapons do not have any actual recoil, both while aiming down the sights or hip firing. All recoil is purely visual. However, using the iron sights will tighten up the shot spread of the gun, allowing for kills at longer ranges. All weapons use Iron Sights in Sandstorm, except the M40A3, which uses the Sniper Scope.
In Modern Combat 2: Black Pegasus, there are two substitutes for iron sights. The MN106 Red Dot, which replaces the gun's iron sights with a red dot sight, and the Dradonitch and M40A3, which both use a sniper scope.
In Modern Combat 3: Fallen Nation, there are five substitutes for iron sights: the Red Dot Sight, the Holographic Sight, the ACOG Scope, the Thermal Scope, and the Sniper Scope, which, as before, replace the default iron sights of all Sniper Rifles. Iron sights have much more detail and complexity in Fallen Nation than in previous titles.
In Modern Combat 5: Blackout, iron sights are the standard sight on most weapons besides sniper rifles. However Blackout offers a much wider array of optical attachments for all weapon types than previous titles. Likewise, various weapons utilize a unique optic as their default sight rather than conventional iron sights (such as the modular weapons of the X1-Morph class, which come with custom red dot sights).