A Compensator is a firearm attachment which improves weapon stability during repeated or automatic fire by venting gases upwards. This counteracts the potential of the muzzle to flip to either side. As a consequence, the visible flash of the weapon may be even greater than without a compensator.
— Battlelog description
The Compensator is a barrel attachment featured in Battlefield 4. The attachment reduces the horizontal recoil of a weapon by 25%, at the expense of lowering the accuracy of a weapon when fired continuously due to a 30% increase in bullet spread. It is the counterpart to the Muzzle Brake, which decreases vertical recoil.
The Compensator is the default barrel attachment for the MX4, and is unlocked for most other weapons through progression. Semi-automatic shotguns can only unlock the Compensator, along with the Muzzle Brake, through Battlepacks, and it is not available for Sniper Rifles due to their lack of horizontal recoil.
The attachment is especially useful for weapons with high side-to-side recoil, like the F2000, and causes the recoil of the weapon to be mostly vertical, making it much easier to manage. The Compensator has the drawback of making the weapon less accurate, however, due to its 30% increase in bullet spread while continuously firing. This makes ranged engagements difficult and necessitates that the player bursts or tap-fires their weapon to remain accurate.
The usage of the Stubby/Potato Grip in combination with the Compensator, however, can be used to minimize the accuracy penalty. The grip's 15% reduction of spread increase will half the Compensator's penalty for it, and the grip will completely remove the Compensator's effect on ADS accuracy. This makes the combination a very good choice if the player wants to retain most of the weapon's accuracy and have lighter recoil.
The Ergo/Vertical Grip can also help reduce the accuracy penalty by lowering the weapon's minimum spread while moving by 50%. This makes the 30% increase in max spread less noticeable and the overall spread increase lighter, but it should be noted that this only applies when the player is mobile, so the combination is best utilized when in close quarters or if the player has an aggressive play style.
— Battlelog Description
The Compensator is a weapon attachment featured in Battlefield Hardline. Functioning in the same manner as the Battlefield 4 counterpart, it reduces a weapon's vertical recoil and overall control at the cost of weapon accuracy.