Almost every conceivable form of projectile, internal and external, have been made and experimented upon. Auxiliaries to expansion, various.Auxiliaries to expansion have been used, made of metal, horn, wood, and leather, with plugs, screws, or cups of divers shapes. Cannelures are used, of varying forms, depth and number.
Rotation from smooth bores.
It has even been attempted to construct bullets upon the screw principle, so that the projectile should receive spirality from the action of the air upon its outer or inner surface, when fired out of a smooth bore musket.
General characteristics of modern rifles.
The general characteristics of the European rifles, up to 1850, are a very large calibre, a comparatively light short barrel, with a quick twist, i.e., about one turn in three feet, sometimes using a patch, and sometimes not, the bullet circular, and its front part flattened by starting and ramming down.
American alterations.
It appears that the introduction of additional weight in the barrel, reduction in the size of the calibre, the constant use of the patch, a slower twist, generally one turn in 6ft., combined with (what is now known to be a detriment) great length of barrel, are exclusively American.
Picket bullet.
A round ended picket ([plate 20], fig. 16), was occasionally used in some parts of the States, until the invention of Mr. Allen Clarke, of the flat ended picket, which allows a much greater charge of powder, producing greater velocity, and consequently less variation in a side wind.
On the comparative merits of rifles.