The easiest way to fight George is by not fighting him. Shooting him, blowing him up, and even knifing him will cause him to roar in fury, then charging at full sprint toward you and your allies until everyone is dead. If this occurs, you can lead him to any large body of water to calm him down. Until you acquire the new wonder weapon and upgrade it via pack-a-punch, you will not be able to kill him. Also, the power must be active before you can damage him.