None of the real Navies were .44's. Navies were .36's. In addition, the frame may be brass, and it may be case hardened, but it can't be both. If it is a case hardened frame it is steel or iron. Brass will just look like brass.
That being said, there have been copies of Colt Navies that were sold in .44 instead of .36, it could be one of those. A picture would help. I am guessing it is a 1860 Army, or a 1851 Navy made as a .44.
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