The Plattsburg Manual Part 43

"Manufacture. The United States Rifle is manufactured by the Government at Springfield Armory, Ma.s.sachusetts, and Rock Island a.r.s.enal, Illinois.

"Rear Sight Leaf. Graduated from 100 to 2850 yards. The odd range is on the right branch of the leaf, the even on the left. Note that the line corresponding to a range is below a numeral.

"Battle sight is the position of the rear sight in which the leaf is laid down. The slide should be drawn all the way hack to secure full advantage of the windage. It corresponds to a range of 547 yards.

"Rounds. The rifle will hold six cartridges. Five are carried in the magazine and one in the chamber.

"Stock. Made of walnut wood.

"Oiler and Thong Case. Furnished for every alternate rifle and is carried in b.u.t.t of the stock. In one section is a supply of oil, in the other a thong and brush for cleaning the bore. In cleaning by this method draw the brush or rag from the muzzle toward the breech.

"Weight. 8.69 pounds without bayonet. Bayonet weighs 1 pound.

"AMMUNITION

"Cost. About three and one-half cents per cartridge.

"Bullet. Has a core of lead and tin composition inclosed in a jacket of cupro-nickel. The jacket being tough enables the lands in the bore to grip the bullet without rupturing and to rotate it while pa.s.sing through the barrel. A lead bullet unjacketed would strip and pa.s.s through without rotating. It weighs 150 grains and is pointed to offer less resistance to the air.

"Case. Made of bra.s.s. The government ammunition is manufactured at Frankford a.r.s.enal, Pennsylvania.

"Powder. Pyrocellulose. The grains are cylindrical, single, perforated, and graphited. Normal charge is 47-50 grains. Pressure developed in the chamber is 51,000 pounds per square inch.

"Penetration. This bullet will penetrate the following materials to depth stated at range of 100 yards: Moist sand, 14.02 inches; loam, 17.46 inches; oak, 31.18 inches; brick wall, 5.5 inches; steel plate, .4 inch. Dry sand is the best stop. The bullet will penetrate 6.88 inches of it at 100 yards and 13.12 inches at 500 yards.

"Range. Maximum range, 4891.6 yards, about 2-3/4 miles) with the muzzle elevated 45 degrees. The time of flight 38.058 seconds.

"Velocity. About 2700 feet per second at 70 degrees F.

"Weight. A complete cartridge weighs 395.5 grains depending on amount of water. It is waterproof."

ESTIMATING DISTANCE

Suppose you are out hunting, and that you see a big buck on a distant hill. Suppose that it is exactly 600 yards distant from you, that you are an expert shot, and that you set your sights at 400 yards and fire.

Will you hit the deer or not? You must know how to guess accurately the distance to a deer, or a man, or anything else, if you propose to have any reasonable hope of hitting it.

The art of estimating distances with the eye can be improved by practice. When you are in ranks, observe continually your surroundings.

Call attention to and make estimates of the distances to all the prominent objects in view. Others near you will become interested, and the interest will soon spread to the entire company. It will be necessary for the objects to be pointed out to those interested. This in itself is a difficult thing to do. To be able quickly to see distant objects that are being pointed out is a military accomplishment which all soldiers should possess and which comes only with practice.

METHODS OF ESTIMATING DISTANCES BY THE EYE

1. Decide that the object cannot be more than a certain distance away, or less than a certain distance. Keep the estimate within the closest possible limits and take the mean of the two estimates as the range. For instance, that deer cannot be over 800 yards away and not less than 400 yards. Your estimated distance is 600 yards.

2. Select a point which you think is the middle point of the distance, estimate the distance to this middle point, and double your estimate to get your range. Do the same thing with half the distance, if the object is very far away.

3. Estimate the distance along a parallel line, such as a telephone line or a railroad having on it a well-defined length with which you are familiar.

4. Take the mean of several estimates made by several well-instructed men. This method is used in battle, but is not applicable to instruction or during tests.

1. Preliminary Instruction

To estimate distances by the eye with accuracy, it is first necessary that you become familiar with the appearance of the most convenient unit of length, namely 100 yards. Stake off a distance of 100 yards.

Subdivide this 100 yards into four 25-yard divisions. Pace off the entire distance several times, and you will soon become familiar with the appearance of 100 yards. Next, take a distance more than 100 yards and compare it mentally with your unit of measure (100 yards) and make your estimate. Verify this estimate by pacing the distance. Do this once a day for several months, and you may become highly skilled in the art of estimating distances.

2. Preliminary Instruction

If you know how a soldier, or group of soldiers, looks at the different ranges, it will often a.s.sist you in quickly making an accurate estimate of the distance. In order to acquire skill in estimating distances by this method one must have special exercises designated to demonstrate the clearness with which details of clothing, movement of the limbs, etc., can be observed at the different ranges. Have a squad march away from you to a distance of 1,200 yards. Then have it approach you and halt every 100 yards. Each time the squad halts make a mental note of the distance, and then observe carefully its appearance, the clearness with which you can see the clothing, movements of the limbs, etc.

APPEARANCE OF OBJECTS

Become familiar with the effect which the varying conditions of light, background, etc., have upon the apparent distance of the object. Don't be content to memorize the following data, but go after the underlying reason in each case.

Objects seem nearer than they actually are:

1. When the object is seen in a bright light.

2. When the color of the object contrasts sharply with the color of the background.

3. When looking over water, snow, or a uniform surface like a wheat field.

4. When looking from a height downward.

5. In clear atmosphere of high alt.i.tudes, as in Arizona and New Mexico.

Objects seem more distant than they actually are:

1. When looking over a depression in the ground (across a canyon).

2. When there is a poor light (very cloudy day) or a fog.

3. When only a part of the object can be seen.

4. When looking from low ground upward toward higher ground.

ESTIMATING DISTANCES BY SOUND