[terminado]

  It seems unlikely[...]

That's not a particularly substantive comment. Got anything to back up what seems to be the case, according to your opinion?

  the energy effects of a 6.5 mm round at range 

Compared to:

  those of a 5.56 mm round point blank

The behavior of either bullet on a human head, given the circumstances, won't be radically different. Hydrostatic shock, inducing spin on the slug, upon entering the cranium, is going to pop the skull open on exit, and everything in between is going to be shredded hamburger.

The head wouldn't be ripped clean off. It wasn't a 12 gauge shotgun inside the mouth. These weren't explosive shells. They were ball rounds.

[escape_goat]

It's true that my response would be greatly improved had I done the math comparing the kinetic energy of the bullets in the two scenarios. I relied on reports of the results of M-16 shots to the human head at similar distances.

However, having done further reading on the matter, it has become clear that no such bullet as we are discussing actually struck the President's skull. The bullet struck the President's first thoracic vertebrae and exited from his throat. So I do not feel all that badly about the degree of diligence that I invested in my reply.

[terminado]

So share your reading material, rather than leave opaque conclusions, as you search for an exit to the reply chain.