Add a bullet effect to your turret. Make sure that the Set angle property is No and default speed is 0.
On Turret shoot=> Set Turret's bullet speed to x, set Turret bullet angle of motion to (Projectile.Bullet.AngleOfMotion+180)%360, Wait x secs. and set Turret bullet speed to 0
Experiment with bullet speed and wait time to achieve desired effet.
Hope this helps