[4] The weight of powder charge to give the prescribed velocity
will be determined shortly before the test, cast iron projectiles
of proper weight being fired for the purpose; this weight of
charge will be taken as giving the prescribed velocity to the
projectiles undergoing test.

* * * * *

(c) 12-inch deck piercing shell. Two shell, sandfilled to standard
weight, will be fired with a striking velocity sufficient to pass
completely through a 4-1/2-inch nickel-steel protective-deck plate
inclined so as to give an angle of impact of 60 degrees, and to be
supported by a suitable backing of wood; or both shell shall be
subjected to such alternate ballistic test as the Department may judge
to be an equivalent to the above in its effect upon the projectile.

* * * * *

The nickel-steel protective-deck plate shall be manufactured by the
open-hearth process and shall contain about 3-1/4 per cent of nickel,
not more than six one-hundredths of one per cent of phosphorous; not
more than four one-hundredths of one per cent of sulphur, shall be the
best composition in all respects.

It shall be oil or water tempered and annealed, and the whole plate
shall be subjected to the same treatment at the same time.

Tensile test will be made after final treatment. One longitudinal
specimen for tensile test will be taken from each plate. Each shall
show a tensile strength of at least 80,000 pounds per square inch and
an elongation in 2 inches of at least 27 per cent.

Bending tests will be made as follows: A piece cut from the plate shall
be doubled cold around a curve of which the diameter is not more than
the thickness of the piece tested without showing any cracks. The ends
of the piece are to be parallel after bending. These specimens shall be
12 inches long, 1-1/2 inches wide, and 1 inch thick.

At the discretion of the inspector, bending specimens 1/2 inch square
taken with a hollow drill, may be substituted. Such specimens must bend
cold to 180 degrees flat, without sign of fracture on outer surface.

(d) 12-inch Torpedo Shell. Two shell, sandloaded to standard weight,
will be fired from a gun or mortar into a sand butt with a pressure in
the powder chamber of about 37,000 pounds per square inch to test
structural ability.

If the shell are found not seriously deformed by discharge from the
piece and in a con