How do you hack a mounted machine gun in killzone 2

You need the repair skill with the engineer. Once you have the skill, take out the hack/repair tool and press R1 while aiming at the mounted gun close range. It will be hacked then you can use it. You need the repair skill with the engineer. Once you have the skill, take out the hack/repair tool and press R1 while aiming at the mounted gun close range. It will be hacked then you can use it.