i personally think that the shield gun is better than the decoy barrier. like the decoy, the turret you protect with the shield gun is completely invulnerable to machine gun fire and damage by heavy weapons are reduced so you can have a turret up front without being owned by the enemy. if nessecary, you can protect any other turret where but only the barrier decoy can protect itself. A shielded turret in front also draws a lot of fire which enemy machine gun bullets get wasted on. you can also upgrade the shield gun's strength making heavy weapon damage even more reduced
shield guns own!!!! and 2 kenji135's highly rated comment: The minigun doesnt have poor accuracy its just that the bullets are invisible and they travel as fast as normal machine gun bullets