[pestobanana]

So to everyone it's "common knowledge" not to use WD-40 on airsoft guns, because they say it will eat away at o rings. Is there any evidence of this?

I've used WD-40 on guns when I was a newbie about 7 or 8 years ago, and those guns still work fine. The cans themselves actually say that they are good for use on O-rings, in fact synthetic rubber is petroleum based. Some mechanics say they use WD-40 on O-rings with no problems. As a part time instrument repair technician, I was taught to use WD-40 on O-rings to help prevent air leakage in metal insert vents, and to prevent water buildup which affects pitch.