A corrosion inhibiting device for firearms which can fit into the chamber of a firearm or stand on its end is provided. The Device has three main sections. The first section is an inner sleeve having a base which approximates the size of the rim of the shell or cartridge of a particular firearm. Extending upwardly from the rim are a plurality of arms which are circumferentially curved to approximate the shape of a firearm chamber. In between each arm is a space through which a volatile corrosion inhibitor material vapor is expelled. The second section of the Device is an outer sleeve. The outer sleeve is columnar in shape and sized so that it approximates the circumference of the shell or cartridge of a particular firearm. One end is open and fits over the upwardly extending arms of the inner sleeve, and is held in place by an O-ring found near the base of the inner sleeve. The opposite end of the outer sleeve is covered, with the exception that it has a hole formed into it. The wall of the outer sleeve has slots formed into it which equal in both size and number the spaces found in between the upwardly extending arms of the inner sleeve. The third section of the Device is a volatile corrosion inhibiting material. The material is essentially columnar in shape having a plurality of flanges extending from a central core. The material is placed on the inside of the inner sleeve, which is then covered with the outer sleeve. By turning the outer sleeve, the amount of volatile corrosion inhibitor vapor released into the firearm chamber can be adjusted.