Bore Butter
I use Bore Butter in all of my Black Powder guns to protect the barrel and other parts of the gun.
When I receive a new or used gun I clean it in hot water with dish washing soap to disolve the grease and build up in the barrel.
First disasemmble the gun, I use mostly long guns, so this also applies to them.
Thake your gun apart remove the barrel, and if you have a work mate use it as a clamp. Clamp the barrel vertically from it into a bucket of hot water, and remove the nipple.
Pour some dish washing detergent and pour hot or boiling water down the barrel. Put enough water in the bucket to cover the hole for the nipple. Get a cleaning rod with the correct jag and a soft patch and insert it in the barrel. Slide the rod down the barrel to the bottom and wait for the patch to get wet. After the patch gets wet slowly draw it up the barrel to create a syphon. Work the water in and out of the barrel until the barrel comes clean.
Loosen the clamp and slide the barrel up until it comes out of the water. Pour boiling water down the barrel and then dry it out with patches.
While the barrel is hot put a generous amount of bore butter on the patch, put the patch on the jag, slowly slide the rod with the patch into the barrel and work it up and down slowly, from the muzzle to the breach. The bore butter will work into the metal when it is hot and create a barrier like Teflon coating. I do that with every black powder firearm and this prevents them from rusting.
I also put it on the threads of the nipple to prevent them from rusting into the gun. It's made to protect the metal under high temperatures.
I think using it as a lube to cover revolver bullets is a waste of time. The chain fire comes from the back of the cylinder not the front.
Also using No 11 caps on a revolver can cause gaps between the nipple and the cap. It was explained to me that using No 10 caps decreases the chance of chainfire because it has a tighter fit.
Bore butter is probably one of the most important things you can purchase for a black powder firearm, if properly used.