The gunsmith's manual

by J. Parish Stelle; Wm. B. Harrison

Object of Browning.—Browning is done for the purpose of subduing the bright color of the barrel from the sight of game; to bring out the fibres of the metal to show their form and beauty, and also to show whether the metal be free from flaws. It does not prevent barrels from rusting, but rust will not attack so readily as if left in a bright condition. The browning is very certain to make all defects appear, except those designedly hidden, and not only defects of materials but the filing and finishing of the barrel, if not well done, will appear in marks in certain lights. A thoroughly well-filed barrel presents, what may be called, a deep liquid appearance.

Preparatory Process.—The process of browning is simple and cheap, and at the same time serves to protect a gun, in some measure, from rust, and also adds to its appearance. The operation consists in producing a very thin uniform film of rust, or oxide, upon the iron and giving a gloss to its surface by rubbing wax over it, or by coating it with some kind of varnish, as shellac varnish.

Preparatory to browning, the barrel having been filed and polished bright, is rubbed with lime to remove all grease. Some gun makers use wet lime or lime water and then rub in dry powdered lime. The vent holes are to be stopped with wax or wooden plugs, and both breech and muzzle are to be plugged with wooden rods which serve as handles to hold the barrel during the operation. The object of plugging is to prevent the mixture from finding its way into the interior of the barrel and the breech and muzzle plugs also serving as handles, prevent the hands from coming in contact with the barrel, which would prevent the stain from “taking,” and consequently cause a spot of different color from that on other portions of the work. The solution is generally applied with a sponge or cloth, sponge being preferable, until the surface is equally moistened, and after standing in a warm place, generally about twenty-four hours, it is rubbed off with a stiff brush or a wire card. The state of the atmosphere will have much to do with the action of the browning mixture. It can be easily ascertained when the barrels are dry enough to work, as by applying the card, if dry, the rust will fly off quickly, but if not dry, the rust will adhere firmly and the surface of the barrel will look streaky. Some mixtures will dry in twelve hours or even less, but twenty-four hours will insure their being perfectly dry. The process of wetting and brushing, or “carding,” is repeated until the barrel has acquired the desired color. When this stage is reached the barrel is freely washed with hot water, in which a little potash may be mixed. Then wash with clean water and dry thoroughly. A little lime water may be used as a wash to destroy any free acid that may remain in the pores of the metal.

The Processes of Browning.—A browning or rust may be obtained very speedily and well by enclosing the barrels in a chamber and subjecting them to the vapor of muriatic acid. The same end may be obtained by moistening the surface with dilute muriatic or nitric acid. There is another material sometimes used, which is butter or chloride of antimony. It is sometimes called “bronzing or browning salt.” In using this substance, a uniform mixture is made with it and olive oil; this is rubbed upon the barrel, which is slightly heated, and is then exposed to the air until the required degree of browning is arrived at. The operation of the antimony is quickened by rubbing on after it, a little aquafortis.

Browning Damascus Barrels.—Damascus barrels are browned by first burnishing the barrels very nicely, then cover with bone oil; pound, or drop, or strew wood ashes all over, then heat in a wire cage filled with charcoal, until the first dark blue is obtained. After the barrels are cold, mix a small quantity of sulphuric acid in water, and with a hard brush apply to the barrel. The acid will remove the color from the steel portion of the barrel, leaving the iron, on account of its greater adhesion, still retaining its blue color. Take care to keep a good color and not extract too much.

Browning Belgian Damascus Barrels.—The characteristic, bright, wavy appearance of Belgian Damascus barrels is generally “eat up,” and the process is termed “pickling.” The process results in eating away the softer metals from the harder, used in forming the barrel. The preparation used is one pound of blue vitriol dissolved in a gallon of soft water, at the boiling point, and the boiling continued until the quantity is reduced about one-fourth; then let it cool, and pour out into a lead trough. Plug the barrels securely at both breech and muzzle, so that the liquid cannot get into the interior. When the barrels are immersed in the solution, it will act upon the metal in fifteen to twenty minutes. Remove and wash with water, and if not satisfactory, immerse again, until the operation is complete. Pour boiling water over them, and scratch well with a steel brush or card, which will eventually give the beautiful, bright, wavy appearance. Laminated steel barrels may be subjected to this same operation.

Browning Inferior Barrels.—Inferior quality of Birmingham barrels are browned as follows: Dissolve as much muriate of mercury as can be taken up in a glassfull of alcohol. Mix this solution in one pint or more of water. A small quantity of this mixture is poured on a little whitening and laid on the barrel with a sponge, rather lightly. As soon as dry, brush off and lay on a fresh coating. So proceed until the barrel is dark enough, which is generally about two or three days. The effect is to make the softer portions of the metal a beautiful brown, while the harder portions remain quite light. The rusting process is killed by washing in hot water, after which the barrels are suddenly immersed in cold water. This has the effect of heightening the brightness of both colors.

Plain Welded Barrels made to Resemble Twist.—Plain welded barrels are made to resemble twist barrels by wetting a thread or fine cord with dilute acid, and winding it around the barrel so as to make spiral lines, running all along its surface. Wherever the thread touches a slight coating of rust will be formed. The barrel may be treated in this way two or three times, and the spiral windings of the thread will exhibit fine dark lines closely resembling twist barrels. To wind the thread the barrel may be put between the centres of a lathe, and so turned while it winds the thread upon it, being guided by the hand, or the barrel may be supported between centres or put on a rod of wood, which may be turned by a crank or handle.

Barrels may be colored by exposing them to a degree of heat sufficient to produce a blue tinge, and is done to color pistol barrels, but when double gun barrels are soft-soldered together this cannot be done on account of danger of melting the solder. The inner surface of the barrel, which is also so colored, must be polished after the operation.

Smoke Staining.—This method of coloring barrels is as follows: The barrels are washed with a little sulphuric acid, to cause the metal to receive the effects of the gas more readily; it is then washed off, and the barrels rubbed dry. A fire is built with coal possessing as much hydrogen gas and as little sulphur as possible. Burn the coals until they give a clear, white flame, with no black smoke. Pass the barrels through that flame, backward and forward, until the whole are covered with a black, sooty coating. Place them in a damp, cool cellar and let them stand about twenty-four hours, and if the place be sufficiently damp, the iron parts will be covered with a red rust, while the steel portions still retain the sooty coat. Scratch them off with a wire card and rub with a piece of cloth, and wash or polish with water, using on the cloth a little flour of emery. The steel will be found to be of the original bright color, while the iron will be a little darker. Rub dry, and pass the barrels through the flame again. Allow them to stand about twelve hours to rust, and then polish as before. With every smoking the colors will be a little darker. The darkest color to be obtained is a fine purple-black color on the iron; the steel inclining to a copper color.