Proper storage is key to keeping a gun clean
A buddy with a new shotgun still in the box stored it in the trunk of a vehicle for a week or two, and when he retrieved it, he found a thin patina of rust on the metal parts, perhaps the result of humid conditions in the trunk.
That brought up the subject of giving guns a good cleaning before you put them away for a while — like the end of deer, duck, squirrel, rabbit or bird season.
First off, no WD-40!
Countless gunsmiths say, to a man, do not put WD-40 on your guns. Some jokingly say don’t even have it in the same room with your guns, so you won’t be tempted.
A gun coated with WD-40 instead of a good oil will rust — in an amazingly quick time. Yet duck hunters and other outdoorsmen who regularly hunt in wet environments will spray their guns down with WD-40 and forget about them. And days later, they will be shocked at the amount of surface rust they find on their fine firearms.
Spray it down with a proper cleanser
An excellent start to cleaning any firearm is to spray it down with a cleanser that removes oils, grease, burned powders, etc. In the military, rifles and parts were often cleaned with lighter fluid. Once the fluid washed the steel clean, it evaporated, leaving a clean, unprotected surface. Then, everything would be wiped down with an oily rag, with a lightly oiled patch run through the bore.
Nowadays, aerosol cans from gun stores do just that for you — with the ease of a powerful stream of cleanser shooting out of the can, knocking the filth, oils and greases off the surface of your guns. These products are extremely effective and costly.
An excellent substitute is plain automotive brake parts cleaner, inexpensively obtained at any auto parts counter. It works exactly the same way at considerably less cost. Be warned; do not use carburetor cleaners for this job. These petroleum distillates will eat finishes on wooden grips and stocks, and they may melt plastic handgun grips.
Once you have cleaned the burnt powder and accumulated gunk trapped with the old grease and oils, wipe the gun down with an oily rag soaked with a good firearms protectant/lubricant, run a lightly-oiled rag through the bore and put your baby to rest for the long sleep until next hunting season.