Download the editor from here if you haven't....
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Make a backup of your save that you want to edit. Just making a zip file will do.
You can leave the game running while you do this.
Run the RpgMakerSaveEditor and it'll want to open a file. Navigate to your taboo request folder and to your save. Open your save file.
Click on the items tab. Look at #6. Console. It should say 0. Change that to a 1.
File > Save and exit.
If you're running the game, exit to your Title Menu and then load the save. You should have the gun.