James Projectile.—The expanding part of the James projectile consists of a hollow formed in the base of the projectile, and eight radial openings, which extend from this hollow to the surface for the passage of the flame of the charge, which presses against and expands into the grooves of the bore, an envelope or patch, composed of paper, canvas, and lead. In a later pattern of this projectile, the internal cavity and radial openings are omitted, and the outside is furrowed with longitudinal grooves which increase in depth towards the base of the projectile, forming inclined planes, up which the outer covering of lead and canvas is moved by the force of the charge and expanded into the rifling of the piece.
The first projectile used in Parrott guns was invented by Dr. Reed of Alabama, in 1856 or 1857, and was made at Parrott’s foundry. It consisted of a soft wrought-iron cup, slightly swedged to fit the grooves, upon which was cast the body of the shot.
Palliser Projectile.—This is the most formidable armor-piercing projectile in use. It owes its efficiency to the material used,—chilled cast iron. In the later forms the head only is chilled, the body being cast in sand. Both shot and shell are cast with a core. The shell is “blind.” The curve of the ogival head is struck with a radius of one and one-half times the diameter of the projectile.
Parrott Projectile.—Capt. Parrott’s projectile, as now made, is composed of a cast-iron body with a brass ring cast into a rabbet formed around its base. The flame presses against the bottom of the ring and underneath it so as to expand it into the grooves of the gun. To prevent the ring from turning in the rabbet, the latter is recessed at several points of its circumference. Parrott’s incendiary shell has two compartments formed by a partition at right angles to its length. The lower and larger space is filled with a burning composition, the upper one is filled with a bursting charge of powder, which is fired by a time- or concussion-fuze. The burning composition is introduced through a hole in the bottom of the shell, which is stopped up with a screw-plug.
Sawyer Projectile.—The Sawyer projectile has upon its sides six rectangular flanges or ribs to fit into corresponding grooves of the bore. To soften the contact with the surface of the bore, the entire surface of the projectile is covered with a coating of lead and brass-foil. The soft metal at the corner of the base is made thicker than at the sides to admit of being expanded into the grooves, and thereby closing the windage. In the latest pattern of Sawyer projectiles, the flanges are omitted, and the projectiles are made to take the grooves by the expansion of the soft metal at the base, which is peculiarly shaped for this purpose.
Schenkle Projectile.—Schenkle’s projectile is composed of a cast-iron body, the posterior portion of which is a cone. The expanding portion is a papier-maché sabot or ring, which is expanded into the rifling of the bore by being forced on to the cone by the action of the charge. On issuing from the bore the wad is blown to pieces, leaving the projectile unencumbered in its flight. A great difficulty has been found in practice in always getting a proper quality of material for the sabot, and in consequence, these projectiles have not been found to be reliable.
Scott Projectile.—The shell devised by Commander Scott of the British navy, for firing molten iron, has three ribs cast upon it, which fit grooves so constructed as to centre it in the bore of the gun when fired. The interior of this shell is lined with loam to prevent the heat of the charge from penetrating through to the bursting charge. It is supposed to be broken and its contents diffused on striking the object.
Whitworth Projectile.—The cross-section of the bore of the Whitworth gun is a hexagon with the corners slightly rounded. The projectile is first formed so that its cross-section is a circle, and its sides taper towards both ends. The middle portion is then carefully planed off to fit the bore of the gun. The Whitworth blind shell for firing against armor-plates, is made of tempered steel, and each end is closed with a screw. To prevent the heat of impact from acting too soon on the bursting charge, it is surrounded by one or more thicknesses of flannel. A 7-inch shell of this kind has been found to have sufficient strength and stiffness to penetrate 5 inches of wrought iron before bursting.
Confederate Projectiles.—The rifle projectiles used by the Confederates in the late war belonged, with a few exceptions, to the expanding class. Besides the above there are three kinds of projectiles much used in the U. S. service, viz.:
Absterdam Projectile.—The best form is cast in a single piece, and has an expanding ring of brass which projects three-eighths of an inch beyond the base of the projectile.