New US Artillery
So, what were the starting circs when the General Board of the US Navy ordered new naval main guns in 1883?
There was an understanding that the new gun for the best performance should be breech-loading steel rifled, with hard guiding elements. The recoil force was to be transmitted directly through the breech-plug. The gun was supposed to be produced according to the Whitworth technologies best in the world. In general, the prevailing opinion was that a new gun, at least pilot examples, should be ordered from Whitworth.
However, there were certain claims to Whitworth's design with regard to the completeness of the use of the projectile shape. If it is true that the strength of the barrel depends on the thinnest point of the walls metal, then the circular section of the bore gave a more efficient use of metal, and the circular section of the projectile - the best filling factor.
Thus, the projectile was born first. It combined the best elements of the previous designs: Whitworth's general principles, but a circular cross-section, Delafield's technological obturating skirt and six Scott's centering ribs, the guiding faces of which now had to be machined for smoothness. In addition, the front ends of the ribs had to be angled so they interact with the same angle of the rifling entrance to guiding into the grooves when pushing the projectile in any position. Its lead-capped nose pin, as Stafford planned, was not so much to punch a small hole in the armor as to lead to its cracking, after which the bulk of the projectile mass had to break it complete.
However, when the Americans appeal to Whitworth, he, loaded with orders, did not find the opportunity to produce guns on the American plan. The only thing he could offer was the guns of his design. The Americans were no longer satisfied with them. As a result, only equipment for the steel and metalworking plants, as well as some blanks for the barrels, were purchased from Whitworth.
However, with this order, Whitworth was ready to give any advice. The main thing that interested the American admirals was the question, what is the minimum caliber of a gun sufficient to penetrate the side of a modern ironclad? Armstrong was also consulted with this. Both cited the minimum value of 10 inches. However, it was known that Krupp gave his 24-cm guns all the properties of 10-inches. Therefore, the thrifty Americans decided to start with the 9.4-inch caliber as the main of the future New Navy.