US Revolvers were made by Iver Johnson using surplus 2nd Model Safety Automatic frames after they converted to the 3rd Model in 1910. They were sold thru mail order and were cheaper than the standard Iver Johnson, and did not have the safety features of Iver Johnson. The original finish would have been nickel or blues, and it would have had rubber grips with US at the top. Based upon the barrel stamping it appears to be an earlier model, because Iver Johnson added a Made in USA stamp in about 1915 or so. There were actually alot of lower quality copycats made in Europe who tried to cash in on the success of these inexpensive revolvers.
As RJay pointed out, it is considered a black powder frame and is not safe modern smokeless ammunition. Black powder frame means that it should only fire black powder cartridges thru it. Smokeless or modern cartridges
too much pressure and could damage the gun. The were chambered in .22 RF, .32S&W and .38 S&W.
Your gun has many issues, most noticeably the cylinder gap. That gap between the cylinder and barrel should bee within .00" or so, and yours appears to be about 1/8".
These generally don't carry much value, maybe $100, and in this condition it is worth maybe $25. Not many gunsmiths will work in these as the cost of repairs often will often exceed the value of the gun. They are fairly simple to work on and most people who collect them learn how to repair them.