Vortex VolleyG 15

All Titans have a shield ability that activates with the LB button and the Vortex Shield is the first shield you start out with. To unlock this achievement you need to fire projectile ammo on an enemy Titan with your Titan. If the enemy Titan throws up his Vortex Shield to catch the projectiles he will then attempt to fire them back at you. This is when you will need to activate your Vortex Shield to catch the incoming projectiles your fired at him. Once you have them release the shields and send them back to the enemy Titan and the achievement will be yours.