Bore Butter is a product sold by Thompson Center Arms. It is a grease like substance that you use to lubricate patches, bullets, or to seal the chambers of a black powder revolver. They advertise that it eliminates bore fouling which makes loading (in a single shot rifle or pistol) diffiicult after several shots. I have found the product to pretty much work as advertised and I am a big fan of it.
http://www.tcarms.com/mlaccessories/...g/73097409.php I also use it as a rust preventitive as is mentioned in their webpage. I clean my BP guns in boiling water. When I am done, I wipe a patch with bore butter over the whole gun. I also run a bore butter patch down the bore and the cylinders. The bore butter melts when it comes in contact with the hot metal and it spreads around pretty evenly. One problem with this is it usually blocks off the nipples. A few caps are fired with no powder or ball to open them up prior to firing.
Crisco: same application as Bore Butter. In a blackpowder revolver, you put some grease on top of each ball in each cylinder. This is supposed to prevent chain firing and also serves to lubricate the ball and keep fouling to a minimum. It also makes a big mess.