Elmer Keith's advice from 'Sixguns'
My wife, who forced me a couple of years ago to go to a gun show, and buy an 1851 Navy, bought me a book by Elmer Keith for Christmas. This book is something of a classic, I believe, and Elmer is an entertaining writer. He wrote this in 1955 (revised in '61), when he was older, but knew men from the Civil war, the 'Indian wars', etc. You may want to check it out.
Anyway, he has a chapter on cleaning, with some helpful advice, and some humorous remarks. For instance, 'Dismantling fine guns with ill fitting screw drivers is a crime.'
His cleaning methods may not reflect what they did as far back as the Civil War, but they are simple enough that it is possible.
On page 306, he writes,
'When black powder is used, the story is different. The powder fouling must be removed, either with an aqueous solvent solution or just plain water, on a patch, and the gun thoroughly dried and swabbed with oil or solvent. When fired with old corrosive primers, solvent or water is the safest method of removing all primer salts. Cap and ball guns must be dismounted occasionally to get the fragments of broken caps out of the action and to wash the parts, oil, and replace them. A good solvent is excellent for this purpose and if it is not available, nothing is better than clean boiling water. The parts will dry of their own heat and can then be lightly oiled.'
...
'Cap and ball base pins should always be coated with a heavy grease like Rig or Winchester gun grease or some other heavy grease that will stay in place. The base pin is usually cannelured most of its length to hold such a grease.'
...
(from page 307)
'I have seen an old cow-poke's gun with the grips worn away from the steel at the edges of the strap, both wood and ivory, but the gun was clean, oiled, and as deadly as a coiled rattlesnake, and ready for business.'
and almost last, but not least...
'Small children should never be allowed to play with a gun if it has any value, as they will surely ruin it, either by taking it apart, using it as a hammer, or by subjecting it to other abuse...' (He does talk about gun safety with children immediately after this. But I noticed his first comment related to the gun, not the children.)
And near the end, he writes (p. 308)
'What I have set forth did not come from books, greatly as we admire nearly all we have read. It came from personal experience, from thousands of conversations with cow-punchers, backwoods gun packers, gun fighters on both sides of the law, and the reminiscences of battle experienced veterans of all our wars from the Civil War on...'
So they valued keeping their guns clean and oiled, and used boiling water sometimes (it sounds like often). But he also implies some variation, which is probably the bottom line.
Not having wisdom of my own, I shared his.