Three-inch Ammunition.

Fixed ammunition is used in the 3” field guns, and is made up with either common shrapnel, high explosive shrapnel, or common steel shell. The rounds as made up vary in length with the type of projectile used. The ammunition chests of the battery are of sufficient size to take any one of the rounds furnished, so that the number of each kind to be carried is a matter for regulation by proper authority. Each round is issued with projectile filled and fused. The weight of the projectile is 15 pounds, and the total weight of one round is 18.75 pounds. The components of one round are the cartridge case with primer, the powder charge, igniter, projectile and fuze.

The cartridge case.—The cartridge case is a solid drawn-brass case 10.8 inches long; it has a capacity of 66.5 cubic inches, and weighs, with primer, 2.25 pounds. A circular groove is cut in the base of the cartridge case and the groove is painted red for high explosive shrapnel, yellow for common shrapnel, and black for high explosive shell.

The primer.—The percussion primer, known as the “110-grain percussion primer,” contains an igniting charge of 110 grains of black powder in addition to the essential elements of a percussion primer. The purpose of the black powder is to insure the ignition of the smokeless powder charge in cartridge case.

Common Steel Shell.
Common Shrapnel.
Cartridge Case.
Semple Tracer.
High Explosive Shrapnel.
3” AMMUNITION

The powder charge.—The powder is a nitrocellulose powder composed of multiperforated (7 perforations) cylindrical grains, each 0.35” long and 0.195” in diameter. The charge varies slightly for different lots of powder, but is approximately 24 ounces. The charge gives a muzzle velocity for shrapnel of 1,700 feet per second (1600 f/s for shell) with a maximum pressure in the bore not exceeding 33,000 pounds per square inch. At the front end of the cartridge case there is an igniter of black powder weighing about ¼ oz. which assists in the uniform ignition of the smokeless powder charge.

The projectiles.—All projectiles have a copper rotating band 1.2” from the base. This band engages in the rifling of the bore of the piece, and gives the projectile a rapid rotation about its long axis during flight. This causes it to travel straight, point on, without tumbling.

Common shrapnel.—The common shrapnel is a base-charged shrapnel fitted with a combination fuze. The case is of steel with solid base. The shrapnel filling is composed of 252 balls, each approximately 167 grains in weight (42 to the pound). The balls are approximately 0.5” in diameter. The balls are poured around a central tube and rest upon a steel diaphragm, the interstices containing a smoke-producing matrix. The bursting charge consisting of 2¾ oz. of black powder is in the base and is covered by the diaphragm which supports the central tube, affording a conduit to the flame leading from the fuze to the bursting charge.

In action the case is not ruptured upon the explosion of the bursting charge; the head is stripped and the balls are shot out of the case with an increase of velocity of about 274 feet per second. The remaining velocity of the shrapnel at 6,500 yards is approximately 724 feet per second and the time of flight 22 seconds, so that at that extreme range, with the increase of velocity due to the bursting charge, this shrapnel with 21-second fuze will be effective. The weight of the shrapnel with fuze is 15 pounds.

Shrapnel is a projectile containing a great number of hardened steel balls, each approximately ½” diameter, which may be projected from a point in the air (called the point of burst) close to but short of the target. Each ball is capable of killing a man or horse at a distance up to 250 or 300 yards from the point of burst. Taken collectively, the paths of these balls form a cone, called the cone of dispersion. The ground section of this cone is elliptical in shape with its longer axis approximately in the plane of fire. At mid-range when burst at normal height of burst (H. B. = 3 mils), the dimensions of this area are approximately 20 yards wide by 250 yards deep. These dimensions will however vary with the angle of fall, the height of burst, the slope of the ground at the target, and the relation between the linear and the rotational velocities of the shrapnel at instant of burst in the air. A 3-mil H. B. is chosen because this gives an average density of 1 hit per square yard of vertical target area. An infantry skirmisher (standing) with his interval occupies approximately 1 square yard.

Shrapnel has very little effect upon material objects. It is very effective against personnel not protected by cover, or to search an area which is known to be occupied, or which must be traversed, by hostile troops.

Ehrhardt High-explosive shrapnel.—The Ehrhardt high-explosive shrapnel is fitted with a combination fuze and a high explosive head. The case is drawn steel with solid base. The shrapnel filling is composed of 285 balls, each approximately 138 grains in weight (50 to the pound). The balls are poured around the central tube and rest upon the steel diaphragm, the interstices containing a matrix of high explosive.

In time action (burst in air), the case is not ruptured upon the explosion of the bursting charge, but the head is forced out and the balls are shot out of the case with an increase of velocity of from 250 to 300 feet per second. In the meantime the head continues its flight, detonating on impact.

If the fuze be set at “safety” or for a time greater than the actual time of flight, this shrapnel may be used in lieu of high-explosive shell. Upon impact a high-explosive shrapnel is detonated by means of the percussion element of the combination fuze, the head being detonated first, which detonation causes the sympathetic detonation of high-explosive matrix surrounding the balls.

Common steel shell.—This steel shell is high-explosive and fitted with a base detonating fuze. The case is hollow and made of drawn steel. It is provided with an ogival head. The steel shell contains a bursting charge of 13.12 ounces of Explosive D. The weight of the shell with bursting charge and fuze is 15 pounds. The shell is always issued filled and fuzed.

This shell bursts on impact and with great force exerted in all directions. It is a powerful instrument for the destruction of material objects such as guns, intrenchments, houses, stone walls, etc. The effect, however, is very local.

Frankford Arsenal combination fuzes.—These fuzes are point fuzes with combination time and percussion elements for use with common shrapnel. They are of the type known as the ring or “dial” fuze, in which the time train is set by turning a graduated ring which carries part of the train. These fuzes may be reset as often as desired.

Ehrhardt combination fuze for high explosive shrapnel.—This fuze is similar to the Frankford Arsenal Combination time and percussion fuze but in addition contains a high explosive head and detonating element. Due to this arrangement, both the projectile and the high explosive head have a high-explosive shell effect when striking on impact.

The service base detonating fuze.—The details of the detonating fuze and the composition of the detonator are kept secret. A detonating fuze is necessary in order to produce a higher order of explosion by causing an instantaneous conversion of the high explosive compound called “Explosive D” with which the shell is charged. If an ordinary percussion fuze were used only an ordinary explosion would be produced as in the explosion of black powder.

Preparation of blank metallic ammunition.—Blank metallic ammunition will always be assembled under the personal supervision of a commissioned officer, who will be held responsible that it is prepared in the manner prescribed. (G. O. 9, War Dept., Jan. 11, 1908.)

For this purpose there are issued blank-cartridge cases, black powder in bulk, tight-fitting felt wads, rubberine, or other quick-drying paint, primers, etc.

Before assembling, the cartridge cases should be carefully inspected to see that they are in sound condition and thoroughly clean and dry. They should also be tested by trying them in the gun, to determine whether they have become deformed. Any cases that do not readily enter the chamber in the gun or that are otherwise seriously deformed should be laid aside for resizing. After inspecting the cartridge cases the blank ammunition should be prepared as follows:

(a) Insert the primers with the primer-inserting press.

(b) Pour into the cartridge case the proper weight of black powder and shake it down well.

(c) Insert the felt wad and press it down hard until it rests squarely on the powder charge.

(d) Give the upper surface of the felt wad and the inside of the cartridge case just above the wad a good coat of the rubberine or other quick-drying paint furnished for the purpose, using a brush, and allow the case to stand until this coat is dry. Then apply another coat of rubberine paint in a similar manner. The object of using rubberine paint, which is strongly adhesive, is to thoroughly seal the joint between the wad and the case to prevent any powder grains from leaking out, and at the same time to firmly hold the wad in place.

The reloading and cleaning outfit.—This outfit consists of the following parts, and is furnished to each battery:

The bushing is used in the primer-inserting press for the insertion of new primers.

The decapping tool and case holder and stand are used for removing exploded primers from the cartridge cases. A light blow on the rod with a piece of wood or the bronze hammer generally removes the primer.

A powder measure to suit the saluting charge for the gun is furnished, and when level full holds the required charge.

The cleaning brush is furnished for cleaning the cartridge cases after they have been used and should be ordered to suit the size of case for which intended.

Care of Cartridge Cases.—As soon after firing as practicable the exploded primers should be removed from the cartridge case by means of the decapping tools furnished with the reloading outfit. The case should then be thoroughly washed in a strong solution of soft soap and soda to remove all powder residue. It should then be thoroughly dried.

If the cartridge cases are carefully cleaned and washed immediately after firing, not only will less labor be required but the life of the cartridge case will be greatly prolonged.

A good solution for washing cartridge cases may be prepared by using ingredients in the following proportions: 1 gallon of water, 2½ ounces of soft soap, 5½ ounces soda. The mixture should be boiled and stirred until the ingredients are entirely dissolved.

In washing cartridge cases this solution should be used hot and in sufficient quantity to completely immerse the cases.

Neither acids nor solutions of acids will be used for cleaning cartridge cases.