The Development of Armor-piercing Shells
(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.
(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