389. The powder for the 100-pounder and 60-pounder should be of Rifle (or, as formerly called, No. 7):—for the smaller calibres, 30-pounder and 20-pounder, of Navy cannon powder. The cartridge-bags are the same as those prescribed for similar calibres of smooth-bore guns.
390. The Parrott guns have been arranged for the use of a certain kind of projectile, supplied by the inventor. These have reference not only to the calibre and mode of rifling, but to the design of the gun itself. For these reasons, the inventor objects to the use of any other than his own form of projectile in the guns of his invention. This request has been acceded to in the heavier calibres. The shells of Schenkl and Hotchkiss have also been used, however, in the smaller calibres.
It is not considered expedient to describe these projectiles, and it is therefore directed that the Commander, Executive Officer, and Gunner shall make themselves thoroughly acquainted with their construction, and the percussion and time fuzes issued with them, before sailing. The Ordnance Officer will furnish them with any information on these subjects in his possession.
391. The projectiles consist of shells, shrapnel, and solid shot. All rifled projectiles used in the Navy are of the expanding class; that is, forced into the grooves by the action of the charge of powder, and require no other precautions in loading than common spherical shells.
392. It is, however, essential—
1st. That the base of every rifle-projectile, especially the Parrott, shall be thickly greased before entering it into the gun. [39] For this purpose common pork slush, prepared by several washings in hot fresh water, may be used.
2d. That the bores of all guns shall be frequently washed, the grooves of rifled guns cleaned of all residuum and dirt, and a moist sponge invariably used. After firing, the bore should be oiled with a sponge.
The attention of Commanding Officers is especially called to this requirement; and the Bureau desires that the action of Parrott's and other rifle-projectiles fired under the above conditions, may be carefully observed and reported; for it is believed that nearly all the failures of projectiles in actual service result from the grooves being filled, after a few rounds, with a hardened residuum of powder.
393. It is also necessary that the shell shall be close home on the powder, otherwise the necessary expansion will not take place, and the shell will tumble immediately after leaving the gun, utterly destroying its range and accuracy.
394. In order to be certain that the projectile is properly home, the rammer-handle must be marked to indicate it.