Rusty Duck I find at WalMart, the Kroil I get from a local bearing/industrial supply house. That Kroil is some good stuff, I sprayed a dob on a gun barrel right next to a scope base, the dang stuff flowed from on the barrel up into and under the base, you could see it moving, up hill at that. With the Kroil I've been wiping down my guns, apply it around the breech where you get all that fouling, After shooting the fouling just wipes of, it's almost like having teflon coating. Might be good to spary on your scopes to protect against gunk there too.