Much care is taken to give the projectiles uniformity of size;
and if the powder is of suitable quality, those now supplied will
almost invariably take the grooves. Should difficulty in this respect,
however, be experienced, it may be remedied by separating the brass
ring from the iron at three or four points of the circumference. This
should be done with a cold chisel, very slightly, and so as not to
interfere with the loading. It is only necessary to sever the contact
of the two metals.

397. As the projectile slides in the gun with very little friction,
particularly when greased, the gun should therefore be elevated and
eased out when firing to leeward, that the shot may not be started
from its seat. An experiment to test this, showed that running a
100-pounder out with the force of its crew against the forward hurter,
the gun being level, started the shot forward nearly two feet.

Placing a grommet or other wad over elongated projectiles is
positively prohibited.

398. The 100-pounder and 60-pounder guns being, respectively, of the
calibres of the 32-pounder and 18-pounder spherical shot, and fired
with the same charges, these shot may be fired from them with
excellent effect, particularly on ricochet. The round shot should be
sewed up in canvas or felt, strapped to a sabot, or snaked between two
grommet-wads.

399. Both percussion and time fuzes are supplied for these rifle-guns.
When the object to be fired at presents a sufficient resistance, such
as masses of timber or earth, ships, or solidly-built houses, the
percussion-fuzes alone should be used from rifled cannon. They will,
however, frequently fail to explode the shell at long ranges, owing to
the shell not striking on its apex; or, if fired into loose earth,
which checks its momentum too slowly to make the plunger strike with
sufficient force.

400. It has been observed that time-fuzes burn with greater rapidity
in shell thrown from rifled cannon. Being in front, they are subjected
to greater pressure from the air. A similar effect is produced when
the fuze is confined under a water-cap, as in the naval time-fuze.

401. The fuze-holes of the heavy shells are cast larger than the
diameter of the regular fuze-stocks of the navy, which can, however,
be used with the aid of a bouching or an adapting ring, always sent
with the shells.

This bouching has heretofore been made of cast zinc. Others with a
flange and washer and the thread cut are now suppli