Concept
Charles Ragon de Bange (17 October 1833 – 9 July 1914) was a French artillery officer and Polytechnician. He invented the first effective obturator system for breech-loading artillery, which remains in use. He also designed a system of field guns of various calibers which served the French Army well into World War I: the Système de Bange. Many attempts had been made at developing breech-loading cannons, but had only partial success sealing of the breech. When fired, hot gases and burning gunpowder could escape, losing power and potentially burning the operating crew. Rifles, with smaller loads and thus less stress, were able to use rubber in O-rings as on the Chassepot rifle. The same principle of breech sealing applied on cannons was not as easy to develop. Several materials were able to hold the pressure and heat of cannon fire, but did not expand like rubber, thereby failing to provide a tight seal. The most successful of those designs was the Broadwell ring invented by American engineer Lewis Wells Broadwell (who worked as a sales agent for the Gatling Gun Company in Europe) in early 1860s and widely applied (without a license) by the Krupp company on their breech-loaders. In 1872, de Bange designed the de Bange system, a new type of obturating ring for breech-loading artillery pieces. His system utilized the same general principle devised by Andrew Hotchkiss ca. 1855 for his rifled muzzle-loading projectiles, where two parts of the shell squeezed a soft (in that case lead) ring under the pressure of gunpowder fumes to obturate the barrel (see Rotation of ammunition), and used a breech block made of three parts; an interrupted screw locking mechanism at the rear, a doughnut-shaped grease-impregnated asbestos pad that sealed the breech, and a rounded movable "nose cone" at the front. When the gun fired, the nose was driven rearward, compressing the asbestos pad and squeezing it so it expanded outward to seal the breech. The French referred to the shape of the breech's nose as "mushroom like", as it resembled the cap of a mushroom.
