Some years ago, I sprayed WD-40 on a number of primers, left them over night, then the next day I put them on a steel bench and hit each of them with a hammer. I don't recall hearing an audible bang, typical from a normal primer ignition, from any of them, but most of them made smoke, so while none would not have initiated the powder charge in a cartridge reliably, the danger of hangfires could not be discounted. At that point I began to doubt the wisdom of soaking primers in oil, then declaring them inert.