While most of the modern books on gunsmithing give numerous formulae for browning or blueing rifle barrels they are all intended for use on cast-steel or modern steel barrels and do not give good results on the soft iron barrels of the old muzzle-loading rifles. The following cold browning formula was given by Colonel Townsend Whelen in his book, Amateur Gunsmithing, gives nice results on soft iron or soft steel barrels and has been used by hundreds of rifle cranks and gunsmiths with excellent results.
Tincture Ferric Chloride, 1 ounce
Alchohol, 95% by volume, 1 ounce
Bichloride of Mercury, 1/4 ounce
Nitric Acid (sp. gr. 1.40) 1/4 ounce
Copper Sulfate, 1/8 ounce
Distilled Water, 1 quart
Make up a few days before needed and keep in a dark brown bottle.
Grease the bore of the barrel with any good gun grease; plug both ends of the barrel with tight fitting hardwood plugs to use in handling the barrel thereafter. Clean the barrel thoroughly after having polished it well--the better the polishing, the better the browning--with lime soda and sal soda solution to thoroughly remove all grease or oil, else the job will be a failure. A solution of lye may also be used to remove the grease or oil. Some gunsmiths boil the barrel in a solution of one heaping tablespoon of lye to each gallon of water, while hanging the barrel by wire hooks attached to the wood plugs.
When the barrel has been thoroughly degreased, boil it a few minutes in clear water and rinse in a second water. Then, handling only by the wood plugs, quickly wipe the barrel dry with a clean cotton cloth that has been boiled and dried; do this quickly else rust spots may start while cooling. Better wear cotton gloves while doing this work. Apply the browning solution with a clean cotton swab, not too wet but damp enough to prevent the solution running. Go over entire length of the barrel at each stroke of the swab and try not to overlap the strokes. Set aside in a warm, damp place until a red rust is formed over the whole barrel, then scratch it off with a wire scratch brush and steel wool. Repeat this every 10 or 12 hours until the color suits; then boil the barrel to stop further rusting. Dry it and apply a coat of linseed oil; when the barrel is cool give it a coat of light oil and let it stand a day or two to harden.
From three to ten days are required to throughly[sic] brown a barrel in this way, but when finished the color is a dark brown that never comes off. It is best to boil the barrel a few minutes after each scratching as this prevents streaks and spots. Be sure the hands do not touch the barrel while browning and handle it only by the wooden plugs in each end.
The late George C. Schoyen's rifles usually had beautifully browned barrels, and the formula for his browning solution was furnished by my friend Major Jerome Clark, U.S. Army Retired. This browning works equally well on soft iron or soft steel barrels, but not on nickle or other hard steel barrels.
