The shell used by our Army before the war had been largely of the base-fuse type. Interchangeability of ammunition with the French required that we adopt shell of the nose-fuse type. The boosters and adapters that went with this type were unfamiliar to our industry.
The adapter is the metallic device that holds the booster and fuse and fastens them in the shell. The adapter, therefore, is a broad ring, screw-threaded both outside and inside. The inside diameter is uniform, so as to allow the same size of booster and fuse to be screwed into shell of different sizes. The outside diameters of the adapters vary with the sizes of the shell they are made to fit, the rings thus being thicker or thinner as the case may require. Fuses of several sorts are employed by the modern artillerist; and with shell equipped with adapters, any fuse may be inserted in the field right at the gun.
Unexpectedly the manufacture of boosters and adapters proved to be much more difficult than it appeared to be at the start, and the shortage of these devices was a limiting factor in the American production of shell.
On May 1, 1917, drawings and specifications were sent to the principal manufacturers of ammunition and ammunition components inviting bids on 3-inch ammunition. These bids were opened on May 15, 1917, and after full discussion with the Council of National Defense orders were placed for 9,000,000 rounds of 3-inch shell and shrapnel ammunition. The bids for shell and shrapnel ammunition for all the other calibers of guns and howitzers we had on hand then were about to be asked, when the French mission to this country arrived; and the sending out of proposals was deferred, while discussion ensued as to changing our 3-inch and 6-inch artillery to 75-millimeter and 155-millimeter calibers, so as to make our ammunition interchangeable with that of the French. This decision was made June 5, 1917.
There then took place much discussion and consideration of the French ammunition. The French had several distinct types of shell, ranging from the very thin walled high capacity kind to the thicker walled types. The French specifications were radically different from our own or those of the British. The steel shell in the French practice was subjected to a drastic heat treatment, which did not seem necessary to us for the thicker walled types of shell.
The French fusing system also was entirely different from that used by our service. French fuses were carried separately, and the adapter and the booster casing were screwed permanently into the shell.
Our decision to adopt French types of ammunition made it necessary to rearrange all our plans, and to obtain drawings of the shell, boosters, adapters, and fuses from France. This caused much negotiating, and a considerable amount of time was consumed in getting the necessary specifications and drawings here.
As a result of recommendations from French officials against production in this country during 1917 of the so-called "obus allongé" and the semisteel type of shell, no attempt was made to produce these for the 155-millimeter guns and howitzers during the first year of the war, but as a result of new recommendations and investigations of our officers in France in the spring of 1918 both of these types of shell were put into quantity production here. When the armistice was signed they were being turned out in such quantities that it appeared that there was sure to be an ample supply on hand in the early spring of 1919.
Radical differences of manufacture existed between the French and British in the matter of specifications and methods of production. Large quantities of British ammunition had been made in this country, and we had adopted the British 8-inch howitzer, so that it appeared we should use British practice in the manufacture of shell. Manufacturers claimed that great delay would result in the production of shell here if the heat treatment and hydraulic tests were insisted upon as the French specifications called for, and investigation proved this to be essentially true, as no facilities for heat treating and hydraulic testing existed.
The upshot of the entire matter was that it was decided to use French dimensions and shell for the 75-millimeter and 155-millimeter calibers so as to obtain uniformity of ballistics, but to permit American metallurgical practice to obtain in the manufacture. Shells made under these specifications were tested by the French commission in France. The verdict on these shell can be summarized in this quotation from their report: