Rust prevention, historically period

Swab with Tow and water, dry with Tow, grease (lard, bear, other) and/or oil (olive, bear, other).

Most of the primary documentation I've found discusses cleaning and protecting the outside of the barrel or the working parts of the lock. Here's one about cleaning the bore, and it has something old and something new.

George Edie
A Treatise on English Shooting
(London 1772)
"When a person is master of a good Piece, the keeping it in proper order is a main article in the doing execution with it: it is necessary the inside of the barrel, the touch-hole, and the lock, be kept clean; and the springs and moving parts of the lock properly oiled. The barrel should be washed at least after every eighteen or twenty fires, where the best sort of powder is used; but if the gun-powder is an inferior sort, then the barrel will require oftener washing. The best method of washing a barrel is, by taking out the britchpin; but as this can seldom be conveniently done, take the barrel out of the stock, and put the britch-end in to a pail of warm water, leaving the touch-hole open; then, with an iron rod, with tow or a bit of linen rag at the end, draw up and down in the syringe manner, till it is quite clean; changing the water, and rinsing the inside, as the foulness requires: when this is done, it will be proper to put in a red-hot iron, of six or eight inches in length (which any blacksmith will furnish), and move it up and down to dry any remaining damp: the outside of the barrel should be well dried, and a little oil rubbed over every time of cleaning."

www.scribd.com/document/292985859/The-Care-and-Clean…

Concoctions for protecting the outside of the barrel are sometimes a bit weird, and show that the modern practice of using exotic things to clean and lubricate the guns and patches had an early start. They didn't have transmission fluid or window cleaner, but they had fat snakes, apparently.

RECIPE FOR MAKING A PASTE TO PREVENT GUN BARRELS
FROM RUSTING, WHETHER IRON OR STEEL
Take an ounce of bear's fat, half an ounce of badger's grease, half an ounce of snake's fat, one ounce of almond oil, and a quarter of an ounce of pulverized indigo, and melt it together in a new vessel over a fire, stir it well and put it afterward into some vessel. In using it a lump as large as a common nut must be put upon a piece of woolen cloth and then rubbed on the barrel and lock of the gun, and it will keep the  barrel from rusting.
-- from John George Hohman's
POW-WOWS or LONG-LOST FRIEND
"A Collection of Mysterious and Invaluable Arts and Remedies,
for Man as Well as Animals -- With Many Proofs" 1st printed in 1820

Animal fats were in common use.

Orderly book of Col Meredith’s Command of Independent Militia Companies at Hampton near Williamsburg, on home guard:
July 11.th 1776
Parole Hampton
That each Soldier make a Leather cover to the Steel of his gun which is to be kept on the same--each man Provide himself with an oyl Cloth which he is to keep constantly by him to Prevent his Arms from taking rust--The Quarter Master is Directed to make application to those Persons who may kill any Mutton or Lambs for the Legs, which are to be Served to the Different Companies to oyl the inside of their Locks.

We know they used tow to clean and oil the bores, but I've never found a direct description of that. If anyone has, I'd like to see it posted.

Spence

Yeah, I tried that once many years ago on one of my earliest treks. Found a copperhead while gathering wood for my supper, wound up roasting and eating some of it. I don't remember any snake fat, though. 

www.youtube.com/watch?v=Fy1L9UT05gA

Spence

I imagine it was just for the color. The recipe is for the outside of the barrel, apparently.

Spence

Coloring the outside of the barrel was apparently not a rare thing.

_A handbook for riflemen; containing the first principles of military discipline, founded on rational method, intended to explain in a familiar and practical manner, the discipline and duties of rifle corps: conformable to the system established for the United States military force, and the latest improvements in the modern art of war_, William Duane, 1812

"To Preserve the Rifle from Rust"

"It must be obvious that the rifle barrel should not be bright; that the equipments of riflemen should be free from everything that is glittering or of a striking color, must be perceived upon every consideration of their duties. Great care, however, must be taken, in the frequent inspection of the rifle, to guard against any neglect of keeping it in order, when it has been browned, greened or blacked.

"The barrel may be secured against external rust, by the following means… If it be intended to give the barrel a clean black color, take half an ounce of camphor, a gill of oil of turpentine, a gill of Florence oil, and a clean earthen cup, simmer them over a fire without flame, until the whole shall be incorporated, and in an uniform liquid state, putting the camphor in last; add to this liquid an ounce of clean white bees wax, and melt the whole, adding a little sweet oil or turpentine to preserve its consistency to the state of honey, add an ounce of powdered black lead to this composition, and the barrel of the rifle being perfectly clean, the composition may be put on like paint, very thin, laid by to dry, and polished to a smooth surface.

"To give the barrel a red or brown color, add red lead or ochre, instead of black lead.

'To make the barrel green, add verdigrease, which must be first ground in oil; to make the barrel blue, pulverised Prussian blue.

"The barrel may be preserved bright and safe from rust by this varnish, without adding any color to it; but it must be laid on very thin, and with great care; and the lock plate and parts open to the air, may be protected from rust by this camphor varnish."

Spence

Wm. Duane also had opinions about cleaning the inside of the barrel.

"The greatest care should be taken in preserving the interior of the barrel clean, and the lock-careful shooters wipe out with flannel or a clean cotton rag, at every 8 to 10 shots, others 20; no iron instruments should be used in cleaning; the spiral brush of hog bristles should be used to scour with hot water; the woolen brush composed of layers of wool, alternately placed across the opening of a piece of hickory, split 4 times, to a length of about 6 inches; the ends of the wool make an excellent brush. After washing clean and drying, the inside should be lightly touched with oil."

Spence