Tom Clancy's H.A.W.X.

This must be done online. This weapon in particular is quite annoying to obtain kills with. Although the "Cannon" sounds lethal or missile-like, it isn't. The cannon is actually a turret/machine gun mounted on the wings of the plane. You can only get kills with this if your enemy is close by as it does not have a large range and it is quite inaccurate. If you are going for this trophy, I suggest you pick on one specific enemy, damage him first with a Joint Strike Missile, and then finish him off with the cannon when he is close enough. If you are having a hard time with this, you could find boosting partners through THIS thread.