Abstract: A desiccating device for preventing corrosion within the barrel of a firearm includes a moisture pervious tube filled with moisture absorbing desiccant material. The tube extends the full length of the gun barrel, with its inner end being plugged and extending into the firing chamber. A cap is mounted on the outer end of the tube, and includes attachment means such as a permanent magnet to hold the tube in place and close the muzzle end of the barrel. The device also provides a safety feature, since the inner end of the tube prevents accidental placement or storage of a live bullet within the firing chamber.