Well, just for fun, I took a large pistol primer, and removed the anvil. (Yes, I know, it's dangerous and don't try this at home!)
Then I sprayed the inside with WD-40 and G96 Gun Treatment, and put in a drop of kerosene. Left the mess sit for 24 hours. Drained it, replaced the anvil, loaded the primer into a cartridge case (.45 ACP). Meanwhile I put a charge of Unique in a cup, sprayed and soaked, using the same items. After the same 24 hours, I drained the liquid off, loaded the oily powder in the same case as the "treated" primer, and followed up with a lead RN bullet. Into the gun, pull the trigger and...BANG! The noise seemed a bit weak, but the bullet went on its way.
Maybe some primers/powder would have been deadened, so I can't say absolutely that they won't be. Maybe other solvents or substances would do so every time. And I certainly don't advise spraying penetrant around live rounds that your neck may depend on. But as for spraying or soaking a loaded gun and then declaring it safe, myth busted.
Jim