I'd just like to point something out to you who use 'boiling hot water'. Rust is 'steel cancer'. Once it has started, even a little, it is always there. And it does not go away until, like cancer, it is CUT AWAY. And if it is there, it continues to slowly get worse. It will start with a light dusting - a little brown/red colour on a patch - an that is the beginning of the end for your barrel, or lock.
You all may do and use whatever system you wish...it's your rifle. But I will not jeopardize my valuable and wonderfully shooting rifles.
I remove the lock and barrel from every rifle, regardless of attaching system, from the wood. If percussion, I remove the nipple with a wrench that fits it well, and I clean it with a toothbrush in water. No soap. (Soaps and detergents contain salts and bases that have an affinity for iron molecules.) I fill a vessel with water at room temperature, in my case a 14" length of black plastic pipe with a wooden plate dropped into the bottom for the tang. The block has a hole drilled to receive the tang so the breech of the barrel itself, and not the tang, rests against the bottom. I use a a stainless rod with a comfortable handle and a jag reduced in diameter to allow using at least two thicknesses of flannel cleaning patch material. I wet the patches, place them over the jag, and introduce it into the bore holding the barrel vertically. This combination must be very tight. It requires determination and effort to push and pull the patch up and down the barrel, allowing the water to come up to the top by the vacuum, and then forcibly push it down hard, blasting the water under great pressure out of the vent, or in the case of a percussion rifle, the empty nipple seat. It only takes about ten such strokes to remove all of the fouling from the rifling and especially from the breech where it will have caked on hard over the coarse of the day's shooting.
Since I used tepid water, the bore will stay wet without oxidizing long enough for me to wipe down the outside with a towel, stand the barrel muzzle down against the bench, and dry and change the cleaning rod to new patches. I mount the barrel in leather pads in my bench vise, and swivel it a bit so I can run the drying patches in easily. Again, these patches are a tight fit and some considerable effort is needed to push and pull the patches through the bore. But you have two hands with which to work, so a tighter combination is possible than just holding the barrel vertical in one hand, and drying it with the other.
the patches again are doubled, and the first pair comes out wet and quite dark. It looks like you didn't get all of the fouling out. Persevere. The next pair come out less wet and not as dark. The third pair come out with no discolouration, and the bore does not want to release it's grip on them. The forth pair get a shot of WD40, and I squirt lots of the same fluid into the muzzle. I will have placed a towel over the vent to receive the blast of WD 40. When I push the WD40 wetted patches in, I use some vigor, and the liquid in the bore is blasted out of the vent. With it, I trust, comes any vestige of water that may have remained at the junction of the breech plug and bore.
Remove the barrel from the vise, wipe it down with the same oily patch(s), and stand it on it's muzzle while you clean your lock with a toothbrush and a pot of water. I use the same water I just used to clean my barrel. Then I use am air compressor to blow all of the water away from the lock, inside and out. I hold the lock on a towel, and squirt locks of WD 40 on the lock on both front and back, and then again, blow it ALL away with the air compressor. I lubricate the bearing surfaces with molybdenum grease, not oil, and then clean the fouling away from the stock. I rub the stock down with a towel, and reassemble it.
Last, I store the rifle muzzle down on a wooden support in my lock-up. I do not want any oil in the barrel from travelling down the rifling and exiting the vent to damage the wood. Ever seen an old Winchester rifle? They are often black around the action from too much oil. The wood is hugely compromised with oil soaking, not to mention the stock's finish.
To the originator of this thread...what you have is a valuable and lovely old rifle that deserves the best care you can provide. Choose the system that will preserve the rifle 100 %...do not compromise through lack of information, or worse, laziness.
It took me longer by far to write this than it would have taken me to clean a rifle.