IMHO, the first assessment is correct; the gun was made of plain steel and nickel plated in the U.S., not at the factory. It shows signs under the plating of having been buffed and polished unevenly.
The Beholla (the name is a combination of BEcker and HOLLAnder, the original maker) is not a bad pistol but more a collector piece than a shooting gun. They are fairly common and bring around $250-300 if in good shape.
As indicated above, manufacture was taken over by Stenda and the gun is also called the Stenda.
The crown/N proof mark indicates that the gun was proved with nitrocellulose (smokeless) powder (as opposed to black powder) and has nothing to do with the type of metal from which the gun was made.