Gunpowder is indeed a corrosive substance. The heat generated by the bullet as it travels through the barrel of the firearm adding the friction between the bullet in the barrel can oxidize the inside of the barrel. Environmental humidity can also cause oxidation in some firearms.
For those of you who carry your firearm in hidden holsters or stick your guns to your body, your transpiration combined with the temperatures and humidity, plus the entry and exit of cars and buildings with air conditioning systems and the exposure to other pollutants can also cause oxidation in some firearms or in their sights and the screws and pins exposed to these elements.
As a result, firearms should be cleaned after each use, or at least once a year if you don’t use the firearm at all. The annual cleaning and immediate cleaning after each use will help extend the life of your firearms. As a precaution, also dry, clean and properly lubricate firearms that have been exposed to any liquid. Proper cleaning, lubrication and maintenance of your firearms will help to conserve the value of your firearm and prolong its life, ensuring proper operation when you really need it. The improper maintenance of firearms is one of the main reasons that cause mechanical problems with firearms. Excessive lubrication can cause excessive carbon buildup, gunpowder, dust, copper particles and other matter that could cause, worst case scenario, problems with your firearm.
Although there are no records of firearms having had mechanical problems caused by the excess of lubricant, in several cases where guns and shotguns are locked, and lack proper maintenance tend to result in bad news. As a rule of thumb, firearms should be cleaned after each use and if they are not fired, they should be cleaned at least once a year. This recommendation will help ensure the proper functioning of your firearm.
Unload the firearm and check it two or three times to make sure your firearm doesn’t have ammunition in the chamber. Repeat this process every time you get your hands on it. There is an astonishing amount of people who accidentally have shot themselves in the hand or have shot another person disarming pistols. Other people have shot their televisions, walls and other areas of their homes when they tried to clean their guns. These people were sure (BIG MISTAKE, make sure by unloading, always) that their firearm was unloaded.
Keep your finger off the trigger at all times and aim the firearm in a safe direction. Never squeeze the trigger to verify that your gun is unloaded. Even when the firearm is unloaded, make sure not to point the gun at anyone, or at any area where it could cause harm to others or their property. Remove the magazine (clip/cartridges) if you haven’t done it yet. The magazine is what feeds or supplies the ammo to your firearm. Once the magazine is removed (keeping your finger off the trigger) check the chamber and make sure there is no ammunition hiding inside it waiting for you to make a mistake.
Verify that the weapon is discharged. With your finger off the trigger and pointing in a safe direction, open the chamber and leave it open if possible. Observe carefully in the chamber area and make a physical and visual inspection of the chamber to make sure there is no ammunition there.