1. Insecticide spray (flame thrower)
Talk to Sgt.Flint in the courtyard in the lower right corner of the map. He wants the protagonist to help him put out the fire.
Then go to the water tank above the house and turn the water tank valve to release water to put out the fire.
You can get it by talking to Sgt.Flint after the fire is extinguished.
2. Death Cannon (Bazooka)
Talk to John Smith in the wooden house in the lower right corner of the map. He will ask the protagonist to go to the designated location to get some rockets and return them.
Go to the designated location and get the explosives from the outdoor box, then place the explosives on the door.
After blowing up the door, you enter the basement. After the rail car is on the slope, it will slide down the track and blow up the door below.
Enter the room and take the yellow rocket, go back to John Smith and get it.
3. Bob (double-barreled artillery)
Talk to Gertrude and you will get part of the weapon's components. The other part needs to go to the mob camp to find it.
Go to the mob camp at the marked location.
After arriving at the camp, deal with the nearby thugs, then go to the wooden house on the hillside and get the key from the table in the room.
Go to the first floor of a building with a watchtower down the slope, find the gun barrel in the house, and assemble it to get it.