I've seasoned cast iron skillets and stuff, but never gun parts. I don't see what it would hurt though as long as you're not cooking them and melting plastics.
Which brings me to another point about ballistol, it can degrade certain plastics. I know of a guy who did some tests on evo scorpion magazines using ballistol on them and within just a few days, the feedlips were failing.
While I don't know what grade plastic that scorpion magazines are made of, the ballistol does seem to weaken it.