Take s look at this...

http://www.shotgunworld.com/bbs/viewtopic.php?t=398836

I've used Hornady's CLP with great success since seeing the results of this less-than-scientific test. Frog Lube would also get s nod, though I've never used it.

I wouldn't vacuum pack a gun. Even with desiccant bags, you want air flow around steel. Using a high quality rust preventer like above and a gun sock when the gun is going to spend some time out of the safe has worked wonderfully for me.

-Leverhead