I think Beauvais was primarily a jeweler, silversmith, or watchmaker, and gun dealer. While there are some firearms out there with his name on them, it is my understanding these were probably built by contract gunsmiths, L. Grimes and A. Sherington. However, that should not diminish the significance of the rifles. They are fine old St. Louis guns.
This one was in Gary Hendershott's
The Old West 2019 catalog:
The cowhorn war club and the buffalo powder horn (which appears to have an attached tip, maybe screwed on) were evidently collected with the rifle by a soldier at Sand Creek.
If you click that link to Mr. Hendershott's catalog, scroll about halfway through it to find this rifle and a pretty good description and discussion. Beauvais is also mentioned several times in the chapter about St. Louis riflemakers in Charles Hanson's book,
The Plains Rifle. In addition, there are little paragraphs about him in Victor Paul's
Missouri Gunsmiths to 1900 and in the second edition of James Whisker's
Gunsmiths and Allied Tradesmen of Missouri. Both edition's of Dr. Whisker's book list Gemienien Beauvais and Jules Beauvais as gunsmiths. Renaud and Jules were brothers, and Gemienien was their father. Renaud (or Renault, or Reno... spelling varies) is briefly mentioned as a silversmith in the first edition of Dr. Whisker's book, under the entry for Jules, but he was listed separately as a gunsmith and silversmith in the second edition. There was also an Augustus Beauvais listed as a gunsmith and silversmith by Dr. Whisker.
In any event, rifles made or marked by R. Beauvais were pretty well regarded.
Notchy Bob