Achieve a high wanted level and go into a restaurant. Shoot everyone with the weapon that you want to raise in rank. If you walk around and wait, police will spawn, but will not shoot you. Police can raise your weapon skill faster than pedestrians. This works best in Burger Shot because of the wide area that you can walk around in. Continue until you reach Hitman status. Use the following trick in front of any safe house. Use the gun you want to get up to Hitman status to repeatedly shoot a car until it explodes. Then, go to the next car. Repeat this until you reach Hitman status for that weapon. Watch out for the police. You can shoot them, then keep shooting the cars. When you are almost dead, enter your safe house and save the game. Your health will be restored and wanted level removed. Get lots of bullets for the guns that you want Hitman or Gangster status for. Go to Tierra Robada. Look around at the north of the island to find a little house. Stay in there and enable the "Increase wanted level" code three times. Stay in the cabin and wait for the police to approach. When they enter the house, kill them. To attain Hitman level quicker, select your desired weapon and go to a Pay 'N' Spray. Park your vehicle directly next to the Pay 'N' Spray. Exit the vehicle and repeatedly shoot people, cars, and cops. When your wanted level is raised to two stars or above, run to your vehicle and drive into the Pay 'N' Spray to cancel it. If your vehicle is not damaged, the respray is free. Wait for the wanted stars to stop flashing, then start shooting people again. Go into a police station and find a room with one entry point, and something that you can hide behind (like a desk). Take out your weapon. You should now have a two star wanted level. Shoot any cop who comes through the door. Every cop you shoot makes your gun skill go up by about five. Do this until you either die, run out of bullets, or enable the "Lower wanted level" code.