In Germany, soon after the beginning of the war, a larger number of firms was available. Before the war, in the latter country, 13 firms were available for the manufacture of the pressed-steel shells for the newly constructed experimental guns. There were no more during the early months of the war.
When, after the first few weeks, the unforeseen extent of the de- mand for munitions was realized, both States had to depart in some measure from the approved methods of manufacture, because it became necessary alsq to utilize factories not equipped with presses. Between December 1914 and the middle of 1915 production began of shells of grey cast-iron for light, and of cast-steel for medium, calibres. About the same time began the greatly increased demand on the part of the troops for explosive shells in place of shrapnel, which was of very little use in position warfare. It was believed that the necessity of the moment was thereby satisfied, but, as might have been anticipated, production on this scale did not in the least respond to the demand. While the shells of Martin steel, formed by pressure, could sustain a firing stress of up to 50 or even 65 kilogrammes to the square millimetre without further treatment, the limit for the cast- iron shells was at the most 25 kilogrammes to the square millimetre. Moreover, the cast-shells could not be secured against faults occur- ring in manufacture. The so-called water-pressure test to which, in both Germany and Austria-Hungary, the finished cast-shells were submitted in the acceptance test, really served no purpose except that of silencing the bad consciences of the experts. The consequence was that these shells had to have their walls considerably strength- ened, and to be shortened, thereby reducing the proportion of the explosive. Moreover, the risk of explosions in the bore forbade the employment of powerful modern explosives as filling, and caused the adoption of much less effective safety explosives such as dynamon, etc. These shells, therefore, proved entirely inadequate, and their production was in fact soon abandoned owing to the number of guns damaged by the splitting or bursting of the barrel. It was contrived, instead, to effect a substantial increase in the output of shells formed by pressure.
The ever greater demands made on the munitions industry, which had to share its raw material with other departments of war supply, made it necessary to employ Thomas iron in addition to Martin steel, and, as ferro-manganese was scarcer in Austria- Hungary after the loss of the Jakobeny mines, to reduce the propor- tion of manganese in the metal. The chief disadvantage of this was that more defects occurred in the manufacture and so many shells were rejected as seriously to reduce the output.
Nowhere did the harmfulness and illogicality of using inferior materials and cheaper processes manifest itself so plainly as in the manufacture of munitions. The war showed clearly that fewer munitions of good quality are much to be preferred to a larger supply of inferior stuff. For nothing so greatly strengthens the moral of the enemy and weakens that of the home army as ineffective ammuni- tion. To this was added the great wastage of gun-barrels (from barrel explosions) with the attendant danger to the men serving the guns. The troops lost faith in their weapons, and were inclined to overestimate the enemy's artillery and underestimate their own.
Acceptance Conditions. The kinds of material to be used in shell- manufacture (for test-pieces) were determined in peace-time. For shell-steel a tensile strength of 80 kilogrammes to the square milli- metre and an elongation of from 7 to 15 per cent; for shrapnel-steel a tensile strength of 80 kilogrammes to the square millimetre and a 12-per-cent elongation. For shells subjected to high pressure for certain guns exceptional strength was required. In Germany particular attention was given in the tests to the limits of extension. As a rule, none of these specifications was modified in war, except in the case of cast-iron shells. Indeed, the testing of the shells was based even more than in peace-time on their shooting. This became, in fact, the only essential test for shrapnel. Any modification of the conditions laid down and tolerances admitted was only intended to facilitate the necessary mass-production, and no sacrifice of quality was accepted. Several over-careful peace-time stipulations could be dropped without scruple. In those cases in which alloy steel was prescribed as the shell material, unalloyed steel came to be admitted when the super-heavy howitzers began to be used for man- killing purposes (especially in the Carso), as such shells needed no hardening process.
An investigation into the causes of the explosions in the bore, which were the source of much anxiety, showed conclusively that they were seldom to be attributed to the shell-bodies as such, and were there- fore usually due to set-up, which in many cases could be very simply ebviated by machining down the body. This was the case, for in- stance, with the Austrian lo-cm. cupola howitzer. The great in- fluence of the brevity of the single effort of resistance required of a shell was demonstrated in an experiment with shells weakened by having the greater part of the circumference sawn through; these were fired with very heavy charges, and all were successful, though the pressure on the dangerous sections must have been greatly in excess of the normal amount. Experiments showed that the cal- culated admissible pressure on the shell body was far less than that which occasionally occurred without rupture.
In reality, the behaviour of the shell in the bore is ill-understood. The pressures to which the shell is exposed cannot yet be mathemat- ically formulated. The calculations made have only an empirical
basis, albeit indispensable. The chief thing is that the material should be of uniform consistency throughout.
Form of Projectiles. -In peace-time the measurements calibre- length, form of head, base were usually alike in Germany and Austria for modern types of shell; i.e. average length, 4 calibres; radius of point about 2 calibres. Those of the medium field army artillery were not very different.
For newer types of gun, i.e. the Austrian medium io-4-cm. and 15- cm., and the German 15-cm., more slender forms were adopted, and consequently the value of improvements in the projectile was more and more recognized, especially in Germany. In order to obtain, with a like weight of shell, the slenderer form and greater calibre- length and at the same time the distribution of mass best suited to rotation, the shells were fitted with ogival caps of thin sheet-metal. These could be removed for the manipulation of time fuzes. The gain in range was 30 to 40 per cent in Germany ; in Austria, jvith the 15-cm. auto-gun it was only 12 per cent. The difference was due to the variations in the ballistic quality of the original shells. Similarly, good results were obtained by Germany for small calibres with the so-called C. shells. The form of these was very carefully defined, and incidentally incorporated a principle which was already being applied by some makers in peace time the streamlined base. The tests carried out showed the influence of these improvements to be only sensible at muzzle velocities of 500 m/s and upwards.
In certain of the heaviest high-trajectory guns the shells used in field warfare were substantially lightened, so as to obtain a great range without over-straining the gun by use of a heavier charge.
Painting of Shells. While the German shells were nearly always streaked with paint, those of the Austro-Hungarian army were left bare except for marks of identification. The painting appears to be more useful for this purpose than as a protection against rust. Before the war various experiments had shown that the formation of rust proceeded under the paint. Moreover, the lack of pigments en- forced their economy in Austria-Hungary.
Driving-Bands. Before the war copper was invariably used for driving-bands. Earlier experiments with cupro-nickel and other alloys led to no result. The size and number of the rings and bands employed are determined by the pressure. An effective pressure on the driving edge of from 400 to 600 kg/cm 2 was found to be best. The form of the rings was only governed by the necessity of good seating of the shell in the bore and by loading convenience. In the case of heavier direct-fire guns a backward strengthening of the bands towards the rear or a gascheck may be advantageous for sealing, according to the shape of the chamber.
The problem of material became especially important when the scarcity of copper began to be felt. The demand could not be met by the internal production, even with the addition of the metal of commandeered domestic articles.
None of the substitutes employed was really of much practical utility. In both Germany and Austria-Hungary the use of a very soft iron resulted in a wearing-out of the barrel after from 60 to 80 shots. Better results were obtained with a pure iron made by an electrolytic process (electrolytic iron), which Germany succeeded in putting to good use as driving-bands; it was, however, difficult to produce in large quantities, and its employment was limited to this one purpose, for which it ranked next to copper in suitability. The wastage of barrels was not excessive. Paper substances gave toler- ably good results both in German and Austro-Hungarian experiments; but the fixing of the paper rings on the shell was very troublesome and not always certain. Besides, the paper had a grinding action on the interior of the bore and led to rapid wear.
A compressed zinc-aluminium alloy, very easily worked, was employed to a great extent, as a substitute for copper, with a thin ring behind or in front of the ordinary zinc band which was of the usual form. While in Germany an extensive use of these driving- bands was being made in 1917, Austria-Hungary from that year onwards effected an increased production by using a hollowed-out gascheck of copper behind the zinc. This, however, was not used in great quantities because at that time the output of ammunition was not sufficient to absorb the copper bands already in hand. The zinc alloy was not really satisfactory, or at most only with the small charges of light howitzers. With more powerful charges the zinc bands were considerably burned through, the sealing was inefficient, and the greatly increased dispersion seriously impaired shooting.
Shrapnel and Shell Shrapnel. The equipment of the field-artillery guns with shrapnel and explosive shells respectively was based on the view prevailing before the war that shrapnel, with its more extended effect and lesser dependence on precision, was the best projectile for use against troops. For the light field-guns the proportion of shrapnel was very high. Various efforts were made to arrive at a " universal " shell, in order to simplify ammunition supply. From this attempt arose the various types of H.E. shrapnel, the fuze of which was so contrived that the projectile could be made to act either as shrapnel or shell. In the end the " universal " shell was accepted by Austria- Hungary alone of all the great States. The Ehrhardt H.E. shrapnel was found the best and was adopted. Three factories were set up for its manufacture before the war. The projectile had pressed into the shrapnel body a head acting like a shell. The bullets were packed in with trotyl. In time shrapnel fire the shell acted as ordinary shrapnel, and also, on the head striking, as a small explosive shell. The effect
