What they called at the time, the New Model Army Revolver (Only later collectors started calling it the Model 1858 Army, based on the patent date that appears on the original revolvers, but that had to do only with the loading lever design). This one is made by Uberti of Italy.
Pietta makes a Sheriff's Model, too. The advantage to the Uberti is slightly superior fit and finish, and Pietta marks up the exposed exterior surfaces of their guns with their name and warnings about "Black Powder Only," and the like. Uberti hides that stuff under the loading lever for better esthetics.
Anyway, the "Sheriff's Model" is just a 5.5" barrel version of the Remington New Model Army Revolver of Civil War fame. I just took delivery on it from Midway USA a couple of days ago. It was originally imported into the US by Taylor's & Company, then to Midway. Remington never produced a "Sheriff's Model," but likely gunsmiths around the country, here and there, occasionally shortened the barrels for customers to make them handier back in the day.
I really like it. It feels great in the hand. Fit and finish is fantastic. Function was 100% during the 48 rounds I fired today. Not a single cap jam of any variety, or failure of any kind.
Wanting to get rid of some 20 years old Triple Seven black powder substitute (still factory sealed in the original container), I used that today (30 grain charges per chamber), along with .454 pure lead balls and CCI No. 11 percussion caps. For lube I used my own blend of lamb's tallow, beeswax, and olive oil. Ignition was sometimes a hair slow (a split second gap between setting off a cap and the main charge detonating), which I attribute to the Triple Seven being 20 years old.
In case you're new to this, the standard procedure is to smear lube over top each fully loaded chamber before capping and firing, which serves the same function that lube serves in standard cartridges, but also serves to prevent chain firing. It also serves to keep things running smoothly because that lube has a way of spreading around, inside and out, when fired.
Here's a 10 yard, six shot, group, fired standing off hand. POA was the orange bullseye. As you can see, the sights came from the factory pretty nicely regulated.
PS Invariably, if there is anyone else at the range when I'm shooting cap and ball revolvers, I get a lot of interest from them about what I'm shooting, which usually results in a long conversation about cap and ball revolvers, and an interest on their part about getting involved in it. I usually give tutorials when that happens.