Jacques-Joseph Plomdeur | Patent for Improvements to Pauly Guns and Mushroom-Shaped Primers, 1825

On March 31, 1825, Jacques-Joseph Plomdeur, a renowned gunsmith based in Paris, was granted a French patent for five years for significant improvements to Pauly guns. Plomdeur, operating his business at 25 rue des Fossés-Montmartre, sought to address the prevalent issues with Pauly’s original design and further innovate by introducing a new type of primer.

Plomdeur identified two main problems in Pauly’s design: the considerable fouling inside the gun’s plate due to the hammer passing through it and the structural weakening caused by modifications to accommodate Roux’s cartridges. Plomdeur’s solution to the first issue was to remove the traditional hammers and replace them with a single hammer positioned internally. This redesign minimized fouling and ensured a cleaner and more efficient operation.

To address the second problem, Plomdeur introduced a novel primer in the shape of a mushroom. This new primer design fit into a modified rosette, eliminating the need to weaken the gun's s...


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