They're talking about rifles, muskets and shotguns. You'll see once you shoot a couple cylinders full through it. Relatively safe? First time you load an unfired percussion revolver how on earth can there be a lingering ember? After that, just use some sense...think. After you fire a cylinder full it's gonna take you a bit to begin loading the cylinder again and any of the mythical lingering embers in a revolver, if you're shooting loose powder and ball, will have long burned themselves out. Unless you're shooting paper cartridges, which are a king sized PITA and not worth the effort as far as I'm concerned, there's nothing to make an ember. This ain't rocket science. Nobody told me spit about percussion revolvers and I never had the first incident. That and there wasn't any internet to screw up common sense.