Try Ballistol, they have a website. Straight as a lube, mixed with water to make "Moose Milk" for cleaning, when the water evaporates, the oil is left.
It is non-petroleum. That being said, BreakFree has never given me a problem with bp guns.
I use WD-40 to wash engine parts, or as a cutting fluid for knife sharpening, even as tapping fluid, but if left on and in a firearmfor a length of time, it will dry to a sticky disgusting coating that has to be washed off with solvent. It is not a lubricant or a good preservative.