Functioning of The Weapon

2. FUNCTION OF THE WEAPON

2.1      Although the weapon has various good characteristics, the accuracy and functioning may still be influenced by:

a. A Dirty Barrel. The pressure of the gas in the barrel influences the correct functioning of the projectile.

b. A Dirty Chamber. The case in the chamber does not expand normally. Possible sticking may give rise to the case not being extracted or being torn.

c. Face of the Breech. Extraction of the case does not take place if the extractor is faulty or damaged. The firing pin will also not function properly if the firing-pin hole is blocked or damaged.

2.2      This may all seem far removed from the theory of small arms fire, but if the working of the weapon is not understood, the term ballistics will always remain a riddle.

2.3      During different shooting exercises the shooter will not attain an acceptable standard if the working of the weapon is restricted owing to stoppages, or if the shooter is incapable of carrying out the relevant correction drills.

3. ELEMENTARY THEORY OF BALLISTICS

3.1      To understand the word ballistics it is necessary to analyse it. Briefly it means the science of projectiles. Ballistics may also be divided into four sub-divisions, which are briefly explained below:

a. Internal ballistics.

b. Intermediate ballistics.

c. External ballistics.

d. Terminal ballistics.

Internal ballistics

3.2      Internal ballistics occurs as soon as the firing pin hits the primer, igniting the propellant, which expands the case and forces the bullet into the grooves in the barrel. This process causes vibrations on the weapon.

3.3      Factors, which Influence the Internal Ballistics

a. Ammunition. Already discussed,

b. Weapon.

      • Dirty Chamber. Correct seating of the case cannot take place. Stoppages may thus arise during the feed and extraction of the case.
      • Damaged Chamber. Expansion of the case cannot take place properly. Stoppages may thus arise during the feed and extraction of the case.
      • Damaged Breech. The breech does not seal properly, and gases may escape during ignition.
      • Dirty (Face of the) Breech. The breech does not seal properly. The firing pin can thus not strike the percussion cap properly.

Intermediate ballistics

3.4      The process begins as soon as the bullet leaves the cartridge case and begins rotating on account of the grooves in the barrel and the gas caused by the propellant, forcing the bullet down the barrel.

3.5      Reaction of the Barrel on Firing. If a shot has been fired perfectly, there should only be a slight upward jump of the barrel before the barrel returns to its original position.

3.6      As soon as the rifle has been fired the recoil system comes into play. There are two main forces involved here:

a. The sudden increase in pressure when the propellant is ignited causes vibrations.

b. The gas escaping from the muzzle when the bullet leaves the barrel causes recoil.

3.7      “Jump” is the variation, expressed as an angle, between the axis of the bore of the barrel before

3.8      Jump is compensated for by an adjustment to the height of the foresight before the weapon leaves the factory.

3.9      Other Factors Affecting Jump.

a. Unavoidable.

      • Varying changes of charge (extremely rare),
      • Varying tolerances in ammunition.

b. Avoidable.

      • Oily Barrel. This causes an abnormal vibration, which causes the weapon to shoot wildly until all the oil has been burned up.
      • Rusted Barrel. A rusted barrel causes the weapon to shoot high because of the abnormal pressure.
      • Incorrect Rest for the Weapon. If a weapon is rested on a hard surface (concrete etc.) the weapon will have an abnormal jump.
      • When an Object presses against the Barrel it has the same effect as above.

External ballistics

3.10      External ballistics start as soon as the projectile and all the gases leave the barrel and the bullet departs on its flight to the target.

3.11      The projectile develops a spinning movement because of the grooves in the barrel. This spinning motion ensures that the round maintains its stability, and that the axis of the round more or less follows the trajectory.

Terminal ballistics

3.12      Terminal ballistics start from the time the bullet hits the target until the bullet has come to a stop.

3.13      Owing to the design of the bullet it is usually stable in flight, but starts to tumble as soon as it penetrates the target. (This is a generalization. This behaviour depends on the shape and characteristics of the bullet.)

3.14      All rounds do not have exactly the same effect. Variations occur because of:

a. The angle of incidence.

b. The speed of the bullet on impact.

c. The composition of the target:

        • Wood,
        • Concrete,
        • Soil,
        • Flesh/living organism.
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