Yes, as Tony wrote, the "Atelier de Precision (AP) de l'Arsenal de Paris" was a workshop where delicate military instruments for artillery and else were developed and engineered, as well as small arms and other equipment. New cuirasses were proofed there. They also collected swords, helmets, cuirasses... on battlefields that were cleaned, restored, and re-assigned. Today, there is only one building left from the Paris Arsenal: la Bibliotheque de l'Arsenal, close to Bastille, which is open to the public and rich of about a million books and innumerable other documents.
When I saw the back of the cuirasse presented by Bob, I immediately thought of a French carabinier cuirasse (I have a complete one) but I have two questions:
- You say it should be a Napoleonic example collected after Waterloo, which is very possible. Is it dated? If not, it could also date back to the Franco-Prussian war in which both carabinier regiments were engaged before being disbanded in 1871
- Being originally French, the back should be maker-marked, usually Manufacture Royale de Chatellerault, or Manufacture Royale de Klingenthal. This should appear under the skirt on the lower part of the back. However, it is written in fine characters and can easily be missed, especially if the metal is oxidized. I was wondering whether you could identify such markings, which also often mention the year of production. The markings may have been hammered by the Prussians though...
This is a great item; congratulations!

