Volley gun
Two notable artillery-sized volley guns were developed in the mid-19th century, although neither was particularly successful in practice. Developed in the 1860s and based on an 1850s design by a captain Fafschamps, the French mitrailleuse is an example of a multi-barreled volley gun that could fire all of its barrels simultaneously or sequentially over a short period of time. Also developed in the 1860s, General Origen Vandenburgh of the New York State Militia designed a weapon that had eighty five parallel .50 caliber rifle barrels. After failing to sell the weapon to the United Kingdom, he reportedly sold a small number to the Confederate States of America, although there is no record that they were actually used. One Vandenburgh gun was located at Fort Fisher, North Carolina, and another reportedly at Salisbury, NC.
Jean Samuel Pauly
Whilst in Paris, Pauly had maintained contact with the weapon manufacturer of Saint-Étienne; using the title "Colonel Jean Samuel Pauly", he established a gunsmith workshop where he designed an automatic bridge and developed mercury fulminate platina. In 1808, in association with French gunsmith François Prélat, Pauly created the first fully self-contained cartridges ; these incorporated a copper base with integrated potassium chlorate primer powder (the major innovation of Pauly), a round bullet and either brass or paper casing. Unlike later cartridges, the case walls didn't provide obturation as the cartridge was loaded through the breech and fired with a needle or a pin; this needle-activated central-fire breech-loading gun would become a major feature of firearms thereafter, and in 1809 Pauly employed the German Johann Nikolaus von Dreyse who would later become the inventor of the famous Dreyse rifle. The corresponding firearm was also developed by Pauly, who made an improved version which was protected by a patent on 29 September 1812, and the cartridge was further improved by the French gunsmith Casimir Lefaucheux in 1836.
It is reported that Napoleon himself said of Pauly's weapons: "Inventions that precede their time remain untapped until general knowledge has reached the same level."