I did see this post earlier but though I would wait and see what other comments surfaced. I have to agree with both Gene and Martin. The obvious discrepancies are the shape of the forewood, the barrel band with the ring on it, the hammer with incorrect "throw" and the strange looking ram rod.

Without being unkind, I would keep it as parts, or maybe a curiosity of backyard manufacture.
I was once told by an old collector friend of mine that if an item does not look right, then it probably isn't. A good maxim for all collectors IMHO.
By the way Gene, how much for the firewood in the pic??