| | -----------------------+------------+-------------------------------- The limiting factor in the development of light field guns has always been the continuous hauling power of 6 horses, which is about 4,000 pounds. The gun has been as powerful as possible within the limits of this weight, which includes the carriage and limber as well as the cannon itself. Improved technique and materials have reduced the necessary weight of the cannon from 1,650 pounds in 1815 to about 800 pounds to-day, permitting the use of weight for recoil mechanism and shield of armor plate without exceeding the limit. The 800-pound nickel-steel gun of 1918 fires as heavy a projectile (12-15 pounds) as the 1,650-pound bronze gun of the Napoleonic wars. The improved material permits a more powerful propellant charge, which results in greater muzzle velocity, a flatter trajectory, and longer maximum range. The latter is due in part also to improved shapes of projectiles and the introduction of rifling. The efficiency of artillery is further increased by the introduction of high-explosive bursting charge. The modern 75-millimeter shell contains about 1.76 pounds of high explosive as against about 0.5 pound of black powder in shell prior to 1893.] The French were experimenting with streamline shell. We adopted the French streamline 75-millimeter shell and put it into production, calling it our Mark IV shell. Our regular 75-millimeter shell, known as the Mark I 1900 shell, had a maximum range of 9,000 yards. The Mark IV shell proved to have a maximum range of 12,130 yards, giving an increase in range of well over a mile. America up to April 3, 1919, turned out about 524,000 of these streamline shell. The French also built shell of semisteel, steel to which iron was added. It was claimed that these shell, by bursting into fine fragments upon exploding, were more effective against troops than all-steel shell, because the fragments of the latter were larger. We adopted this shell also and produced it experimentally. In contour it was a compromise between the old cylindrical shell and the extreme streamline type and was easier to make than the latter. _Artillery ammunition, complete rounds--Acceptances in United States and Canada on U. S. Army orders only._ [Figures in thousands of rounds.]