I do not have any interest in or keep up with the latest BATF rulings on things like pictured above or that are covered by the NFA.
Having said the foregoing, I am not totally without knowledge of such things. YOU MIGHT HAVE A LEGAL PROBLEM, even though you do not have any illegal intent. YOUR ITEM'S DEMILLING MAY OR MAY NOT MEET BATF STANDARDS! If it does not meet their standards you could have a significant legal problem being in possession of it.
Hopefully, others with more actual knowledge of NFA related matters will read and contribute to this thread. I have briefly searched the BATF site for this kind of material, and did not find a definitive answer. Here is a link: http://www.atf.gov/publications/down...-chapter-2.pdf
If I were you, unless I could definitively determine that this thing has been demilled to BATF specs; I would proceed to cut it into numerous pieces and then smash them with a sledge hammer; and then have the pieces to give to the BATF Agents should they come calling. They likely monitor forums like this.