Colt Revolving Rifle Model 1855 - Revolving shotgun, percussion. AF*NM541.
The <a href="https://en.wikipedia.org/wiki/Smithsonian_Institution" class="extiw" title="w:Smithsonian Institution">Smithsonian Institution</a>
<a rel="nofollow" class="external free" href="https://americanhistory.si.edu/collections/search/object/nmah_417930">https://americanhistory.si.edu/collections/search/object/nmah_417930</a>