If you haven't screwed something up, you haven't blued much.
The early Smith's were all blued by one man. He had his own formulation and never shared it with anyone. He did have it written down but his widow tossed it after his death. Or, that's how the story goes. Who knows? I will agree that some of the early work in the coloring process is a little different than today and quite beautiful. Carbona being one example.
The deep liquid look you are aspiring to is mostly about how the steel is polished. Most smiths that offer bluing today simply won't take the time needed to achieve a near mirror polish on the steel.
It can be done. I have done it many times. But, it's work. Real work. It's not just a matter of hitting it with a wheel or two. The final polish is done by hand.
As to your nitre bluing efforts, this process should only be used on small parts.
The finish is not durable enough to last on an entire firearm. Also, with the temperatures needed to achieve the colors, you can seriously change the temper of the steel. Not a good thing when were talking about chambers and receivers. In fact, I use nitre salts to temper springs.
I like to use nitre bluing as an accent. Things like screws, pins, slide releases and safety levers or buttons look good this way. I have made some sterling silver and nitre blued steel to make some unique jewelery.
I am more than willing to share what I've learned over the years but I hate to type. If you want to talk more, IM me your phone #.
I'm in Austin.