Fast travel to the Sawtooth Cauldron and jump over the edge to reach the sawtooth stilts. Turn left and go through the Smoking Guano Grotto until you reach the Main Street Reservoir. Then head straight until you reach the end of the map killing any enemies that get in your way. Now shoot the five barrels in the following order:
1. The blue barrel in front of you.
2. The red barrel to the right next to the hut.
3. The green barrel in the water (it might take some maneuvering to get the barrel to spawn. Either move closer, or more to the right to get the barrel to spawn).
4. The yellow barrel to the left, behind the barricade.
5. The purple barrel to the right.Click here to view the video