Remember folks, WD-40....Water Displacement-40th Formula. Do I use WD40 on my guns? Sure...When they have had over exposure to water. If it gets totally rained on while hiking, gets dropped into a nasty mud puddle, or godforbid gets dropped into a stream/lake/river/whatever, I'll use the WD to displace the water from the surface of the metal and cracks/crevis. But will always follow up with my normal cleaning routine.... 1) Hoppes, 2) WD if needed, 3) Hoppes again to clean the WD out, 4) TetraLube.
I dont think WD40 will actually harm any of the metals, but I do know that it provides very poor lubrication for a firearm. Door hinges...OK, but not a firearm.
Edit: Wow, didnt even notice the date on the OP. You're right Yankee, can we get Mods to lock this one?