It is necessary that all the space between the top rib and the barrels be completely filled with solder, or rust will form there, which will prove of serious detriment to the barrels, and in time work under the ribs, throwing them from the barrels if even a little torsion or springing of the barrels should ever take place. During the progress of soldering, see that the parts are kept pressed close together, and that they do not spring away from each other by their expansion during heating. A small iron clamp screw placed at the breech and also one at the muzzle, is very convenient, as by tightening the screw there is less danger of the parts springing apart. When the breech is soldered and somewhat cooled, the clamp there placed can be removed. These clamps, made of malleable iron, can be obtained at the hardware stores. When the work is soldered and is cool, wash it well with warm water, using a stiff brush to remove dirt and all traces of the acid flux that may remain on the work. With a chisel or scraper remove all superfluous solder and brighten the work with emery cloth or paper of different grades. Begin with the coarser and finishing with the fine or with flour and emery. _Why not Braze Barrels?_—It was formerly the practice to braze barrels together, with spelter solder, at the breech or at both breech and muzzle, but good workmen condemn the practice, as heating the barrels to a high heat in order to melt this solder somewhat diminishes the strength of the metal, and as it is also necessary to again clean and brighten the work after brazing, and to perfectly brighten the flats where they lie together is not so easy a matter. In the life of the gun, it was found to be of no real benefit to thus braze them, as the parts were securely held in place if well soldered with soft solder, and of late years but very few barrels have been thus brazed. Select solder of good quality, put the work well together, and the barrels will remain firmly and rigidly in place, and will not be separated except by unfair means. _Percussioning._—The term Percussioning is used to designate the operations of drilling, and finishing the cone or nipple seat, tapping, putting in the tube or cone (by some called nipple) and otherwise finishing up the parts bearing relationship to the cone seat.