This achievement can be obtained while doing the mission "Code Breaker: Time is Bullets." Since the mission will give you a waypoint to the place where you take the tour. In the map, Sunken Sea, there is a little outlaw village near the bottom left hand corner of the map. It has a Vehicle Station and a Shop located in it. At the entrance of the village you'll see a light-up sign that says "World's Largest Bullet." Upon entering the village, head straight inside towards the shack in front of you. Use the cash box on the side of the shack that has the arrows pointing at it. Once you press , enjoy your errr....tour. The achievement should pop right away. Lastly, you should know that the tour itself costs $8 million, so if you don't have that much you can't get the achievement.