My 1st thought was a Whitney Phoenix prototype.  I started a Google search and found your rifle with questions being asked about what it is on a Reddit thread from 2 years ago.  I also found a Brass Whitney Phoenix that was sold by Collectors Firearms in Houston and another sold at a 2018 Burley auction here in New Braunfels.
My guess is a toolroom prototype proof of concept, the production variant has the external parts that are attached to the action incorporated into the casting/forging to simplify manufacturing.  Just my guess

and that trigger guard.  Not something most folks would bother to work up for a prototype.

Interesting gun tho, kind of like a Flobert.

Could it have started life as a percussion gun that someone converted to cartridge?

That could explaine all the work up to the breech face.

WalnutRed wrote on Feb 10^th, 2025 at 12:25pm:


If you have designed a product that you are trying to get your boss to manufacturer, your pet project, and you work for a company that has very talented workers skilled in all aspects of production, you want to hand your boss a finished product to get your point across.  Not a rough, unfinished rifle.
At a manufacturing plant like I just described, it would take less than 2 weeks to turn that action into this finished product.  Maybe as little as a week.

I'd go along with a percussion conversion of an original semi cartridge with the small hole where in the future a primer would be like some of the very early Civil War (whoops, the War of Northern Aggression) carbines. The excessive length of the protruding firing pin could be where the nipple was that used a musket cap that needed room to slip it on.

Thanks for the suggestions. I still don't know for sure what this rifle really is. However the kind folks at the Cody Firearm's Museum found it interesting enough that they are assisting with research.