I didn't do that test. I tested powders and how bad they rusted over time. But there was a report done in a magazine that went into detail about all the different things to clean and protect the rifles. that might even be the one.

That's an interesting read. The only problem with WD-40 is over time if you let it sit, it can make a varnish of sorts on metal. It does protect metal through. Also while Cosmoline and other greases do protect well, they are hard to apply and remove if you shoot a lot. Although if you were going to put a rifle away for an extended period of time, that might be a good choice..