[MrForbes]

If it is running a shooter, there is almost no load on it, and it won't overheat. What you have to worry about is "stalling" the motor, that is, when you apply a load that is more than the motor can turn, and also apply full electric power to the motor. That will burn up it up rather quickly. And the part that burns up is inside, so a heat sink really won't help. These motors have a cooling fan inside them that turns whenever the motor is turning.