Smokeless powder is the stuff you put in modern self-contained cartridges when reloading them. (9mm, .22, .223, etc.) You specifically do not put it in muzzle loaders for that reason.OK .... that just scared the crap outta me!! I'm new to black powder/muzzle loading and .... what is smokeless powder?? I have been using Pyrodex pellets... is that safe or is it some of this smokeless powder you talk about? I use two pellets (100gr total) in my .45cal. Oh man!! That thing split apart like a plugged barrel or something!!