I'm going to have to agree with the cowboy. I previously used Good old Hoppes Gun oil, but it gummed up a "non shooter" over a winter. On advice from the ar-15 list I completely stripped and cleaned all my semi's that I'd been using the Hoppes on, and re-lubed with Break Free (that's what us civilians use), no problems since.
HTH
BTW: When my wife and I bought a house this last spring, the old lock we were going to use on the shed had suffered from age, it was the same lock that I'd had on my locker in High School. I managed to get some CLP into the channel, it broke it loose overnight, and is still working great! While I hope that none of us abuse our weapons in this manner, I do think it shows just how well Break Free does in Cleaning, Lubricating, and Protecting.
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**P.P.L.L.**