In 1829, Clement Pottet, who had worked for Pauly, took out a patent for a cartridge with a removable base incorporating a pocket for priming compound, or in which a percussion cap could be placed over a central nipple. In 1836, Casimir LeFaucheux, working along different lines, patented his pinfire system. A decade later, Houllier had an idea for a base wad which expanded when fired. It overcame one of the principle deficiencies of early breechloaders – gas leakage at the breech. LeFaucheux spotted the potential, combined the Houllier wad with his pinfire concept and created the first truly successful sporting shotgun cartridge. Both gun and cartridge were displayed at the Great Exhibition in 1851.
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