This is the problem, you don't understand answers when you get them. I suppose my difficulty is that I'm 1) rational and 2) a lawyer so I understand circumstantial evidence, chains of custody, and proper investigations, and I additionally am capable of dealing with the world as it actually exists rather than viewing through a prism of delusional fantasy.
They have not been debunked. There have been multiple tests that confirmed the findings, but my suspicion is that you have no idea what the chemical composition tests showed.
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CE399 is not essential because the path of the bullet can be determined whether or not the actual physical bullet is examined. The fact that it was found and matched to both Oswald's rifle and the fragments recovered from the victims makes the evidence so overwhelming that only someone in total denial of reality can cling to paranoid conspiracy theories.
It's reminiscent of the "missle hit the pentagon" fantasy. They always claim that no plane wreckage was recovered, which is, of course, false, but it doesn't matter. The destruction, severed light polls, skid marks, and pattern on the Pentagon establishes that an airplane hit whether or not any physical remnants of it remained. The fact that A LOT of wreckage was recovered makes it an obvious case.
As I said, your questions have been answered, you just continue to dismiss those answers based on nothing. This is the dance you will do for the rest of your life if you continue to buy into theories with no evidentiary support.
I take it you really, really don't want to answer the questions posed to you. Another dodge. Do you even notice that you're avoiding all these issues, or have you blocked those out in your mind like you've done with all the evidence showing Oswald to be the lone shooter?