I would agree it is most likely a "modern" reproduction. New-made pipe tomahawks were being advertised in in the early seventies, at least. Most really old, original pipe tomahawks that I have seen pictured have a leather wrap or "gasket" inside the eye, between the wood and the metal, to help seal it. Most modern reproductions seem not to have this. You may need to look closely to see it if it is there.
Without perusing the suppliers' catalogs or websites, relying on my sometimes faulty memory, I think a new head similar to that, as a raw casting, will cost you $35 - $40 today. An unfinished handle blank that has been drilled for smoking will run $25 - $30, I think, while an un-drilled haft would be somewhat less. Your pipe tomahawk is finished. I would say you got a pretty good deal for forty bucks. I would have paid that for it, and I don't really even need one. Yours could stand to be cleaned up a little, but I would not clean it much. It has acquired a very nice patina.
It may be tempting to dress it up with file work, inlays, and so forth.
@LRB did a spectacular job with the tomahawk shown in post #6. However, there is a place for the plain, undecorated ones, too, and it would be a shame to destroy that patina. If your pipe tomahawk were mine, I would go over the head with bronze wool and then wipe the metal down with the same surface protectant you use on your guns. Bronze wool will take off surface rust, but won't hurt a brown or blued finish when used judiciously. I would probably clean up the handle with Murphy's Oil Soap, dry it well, and rub in some linseed oil. If the handle has been drilled for smoking, I would get a little
shongsasha and tobacco, and fire it up. I don't think it needs anything else.
Thanks for sharing!
Notchy Bob