+------------------------------+------------------+--------+---------+ | GUN. | Length. | Weight.| Bursting| | | | | Charge. | +------------------------------+--------+---------+--------+---------+ | | Inches.| Calibre.| Pounds.| Pounds. | | 5 inch breech-loading rifle | 17.97 | 3.59 | 60 | 2 | | 6-inch breech-loading rifle | 20.90 | 3.48 | 100 | 4 | | 8-inch breech-loading rifle | 28.10 | 3.51 | 250 | 12 | | 10 inch breech-loading rifle | 35.00 | 3.50 | 500 | 22 | | 12 inch breech-loading rifle | 42.00 | 3.50 | 850 | 38 | | 16-inch breech-loading rifle | 56.00 | 3.50 | 2000 | 90 | +------------------------------+--------+---------+--------+---------+ The armor-piercing shell of the same weight is reduced in length, and its walls are thicker; the bursting charge is consequently much reduced. The following are the particulars, approximately determined: +------------------------------+------------------+--------+---------+ | GUN. | Length. | Weight.| Bursting| | | | | Charge. | +------------------------------+--------+---------+--------+---------+ | | Inches.| Calibre.| Pounds.| Pounds. | | 5-inch breech-loading rifle | 15.07 | 3.01 | 60 | 1 | | 6-inch breech-loading rifle | 17.91 | 2.98 | 100 | 1.50 | | 8-inch breech-loading rifle | 24.25 | 3.03 | 250 | 3.50 | | 10-inch breech-loading rifle | 30.00 | 3.00 | 500 | 7 | | 12-inch breech-loading rifle | 36.00 | 3.00 | 850 | 14 | | 16-inch breech-loading rifle | 48.00 | 3.00 | 2000 | 30 | +------------------------------+--------+---------+--------+---------+ The rifle motion is communicated by one rotating ring of copper, which is placed at the distance of 1.5 inch from the base of the projectile. [Illustration: CARTRIDGE CASE AND GRAINS OF POWDER, U.S.N.] The uniform windage for all calibres is .04 inch; thus, taking the 6-inch gun as an example, the diameter of the bore across the lands is 6 inches, the diameter of the shell is 5.96 inches, the depth of the grooves is .05 inch; thus the diameter of the bore across the grooves is 6.10 inches. In order to permit the rotating ring to fill the grooves, it must have a diameter of 6.14 inches; this causes a _squeeze_ of .05 inch between the lands and the rotating ring.