The Development of Armor-piercing Shells

the submission of a lot to the inspector for selection of samples for ballistic test, and before final delivery, the projectiles must be subjected to an interior hydraulic pressure of 500 pounds per square inch for one minute. All projectiles in which holes, cracks, or any unsoundness are developed by this test will be rejected.

TENSILE TEST

(Art. 28, O. D., U.S.A.)

After forging, the projectiles shall be annealed at a temperature of at least 1,200° F.; and after being annealed, tangential test specimens shall be taken from the base or base prolonged of 2 per cent of the projectiles from each lot selected at random by the inspector.

The tensile strength of the projectiles in a lot shall not vary more than 20,000 pounds from the highest to the lowest.

CHEMICAL TEST

(Art. 30, O. D., U.S.A.)

A careful and complete chemical analysis shall be made of the metal of each heat from which the projectiles are manufactured under these specif