Here's how one researcher tried to explain the roundness of the 7x2 mm fragment.

Just to ask again, are these the only images we have of the 7x2 mm fragment, this gray object below the orange play-doh model in both the left and right photos?
Unless I see this fragment from other angles that proves otherwise, I think this fragment is the object visible in the two X-rays of JFK, from the front and the side.