An easier method would be to launch a grenade at an angle to a wall so that it would bounce off and explode near him. I myself have run over Timmys in boats, stabbed him with a forklift, pushed him off the top of a lighthouse, etc. Have fun killing the Timmys- If you shoot one stood in the water, when he dies he will swim away from you after you killed him.
An easier method would be to launch a grenade at an angle to a wall so that it would bounce off and explode near him. I myself have run over Timmys in boats, stabbed him with a forklift, pushed him off the top of a lighthouse, etc. Have fun killing the Timmys- If you shoot one stood in the water, when he dies he will swim away from you after you killed him.