It is becoming the tendency more and more to eliminate the use of service ammunition in machine guns used for aircraft purposes. This is being supplanted by ammunition loaded with special bullets - armor-piercing, tracer, incendiary, armor-piercing-tracer, and armor-piercing-incendiary. Inasmuch as the pilots are now being protected by armor, it is necessary to resort to the use of special armor-piercing bullets.


ARMOR PIERCING

Two types of armor-piercing bullets have been developed. One consists of a cupro-nickel jacket into which is inserted a hardened steel core weighing about 65 grains, covered with a lead casing, which is so formed as to permit a nose of lead to protrude from t e cupFo-nickel jacket. In the other type of bullet, the steel core is inserted in a copper jacket with a thin lining of lead between it and the core. This is known as the Bowers bullet.


TRACER

In the base of the tracer bullet is inserted a cup of gilding metal, containing a mixture.of barium peroxide, and magnesium. This material 's ignited upon the explosion of the cartridge and burns with a bright green flame which defines its path from the muzzle of the gun up to about 600 yards.


INCENDIARY

The incendiary bullet consists of a flat-nosed cupro-nickel jacket, containing in its nose a charge of 8 grains of yellow phosphorus, held in place by a serrated, plug of lead backed up by a base plug of lead. A small hole through the jacket, located near the junction of the serrated plug and the base plug, is filled with low-fusible alloy, which melts as the bullet passes through the rifle, and permits the phosphorus to ignite. This ammunition is practically the same as the British Buckingham ammunition. The flatnosed type of incendiary bullet is, being replaced by the pointed nose of standard design.


ARMOR - PIERCING - INCENDIARY

This bullet is a combination armor-piercing and incendiary bullet and consists of a cupro-nickel jacket into which is inserted a hardened steel core having a charge of yellow phosphorus at its base.


ARMOR - PIERCING - TRACER

This bullet is a combination armor-piercing and tracer bullet, and consists of a cupro-nickel jacket into which is inserted a hardened steel core having a charge of barium peroxide and magnesium at its base.