<LI id=jsArticleStep1 itxtvisited="1">The chemical constituents of WD-40 are a closely held trade secret. The manufacturer does, however, state that its product contains no silicone. It also does not contain kerosene, water, wax, graphite or chlorofluorocarbons. It does serve to displace water--the "WD" stands for water displacement--and a penetrant. This latter component may render it less than perfect for use on firearms.
Gun oils, on the other hand, may also contain chemicals that the manufacturers state are purposefully included for specific use on firearms. Gun owners typically have their favorite products, so the discussions and arguments tend to be less empirical than conjectural.
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Precious little oil is required to lubricate the actionable parts of a firearm. Excess oil collects dust and dirt and can serve to accelerate wear. Excess lubricant can also gum up an action. WD-40 has fewer lubricating properties than dedicated gun oils.
<LI id=jsArticleStep1 itxtvisited="1">WD-40 will make moisture bead up and run off metal. The bluing on a firearm protects the metal from the effects of moisture when the firearm is being used in the rain, but it can't hurt to spray some WD-40 on a cloth and wipe it over the external metal surfaces of the gun before venturing out in a storm. If a gun has been accidentally submerged, WD-40 makes a great stopgap measure to flush water from the internals before it can be disassembled and properly re-oiled. Many gun owners will not leave a film of WD-40 on a gun for storage purposes, claiming it can promote mildew and that the gun can become gummy. <LI itxtvisited="1">While you can use WD-40 to clean your gun, it is not intended as a cleaner. Still, it will do many things for which it was not intended. Its actual intended purpose, as the manufacturer will tell you, is as a water displacer. That is what the WD stands for. Since you have experience in using it as a cleaner, go ahead and use it on your gun as a cleaner. It sure won't hurt anything. My only caution would be that WD-40 is not a metal protector. It lacks the rust inhibitors that gun oils have. Once you clean your gun, wipe off all of the WD-40 and replace it with a light coat of gun oil.
<LI itxtvisited="1">This question comes up a lot, let me (again) try to answer it for you.
WD 40 was designed as a water displacer for use on titan missle systems. It is a water displacer, and it does work fairly well as a penetrating solution on rusted or siezed bolts etc.
It is NOT a firearm lubricant, and in fact has no lubrication qualities at all once it dries. In fact, when exposed to heat (like on a firearm) it turns gummy. Once dry IT DOES NOT LUBE OR PROTECT A FIREARM. Yes, it can cut thru some cruddy buildup, but then you need to clean the firearm completely and relube it with a proper firearms rated lube. I prefer, and highly recomend that you use Break Free CLP to clean and lubricate any firearm. I have used it since it was first introduced and swear by it, as does most police departments, sheriff's offices and the U.S. military except in the talcum powder sand conditions like Iraq, there they use a dry lubricant.
When Breakfree dries, it leaves behind a proved dry lubricant to protect your firearm.
WD 40 has some unique uses, like removing tar from a cars paint, getting moisture out of a dristributor cap etc, but has NO PLACE on a firearm. Yes, I know a few rednecks and illiterates who insist it works just fine, but then again, they believe duct tape and bailing wire are the answers to all the worlds problems.
shoot safe.