Brugioni said he was shocked at the size of the explosion, indeed, they all were. They were looking for evidence of how many shots and from which direction, but what they saw at that moment, was a huge explosion from JFK's head. I would certainly be shocked by it, and I'd remember it--seeing a huge white cloud shoot up out of the top of Kennedy's head!? Four feet in the air!? None of which we see in the extant film.
I sincerely doubt that, that night, they were getting up close and personal like we do, these days, parsing the number of hairs on his head, which direction he was facing, which bullet hit where, and which one hit first, etc. That would come later--with a real analysis. That was done at Hawkeye Works--and they realized they had a big problem.
Notice, too, Brugioni pointing out to Doug that strange, ultra-black paint job on the back of K's head--like he's seeing it for the first time! Bullseye, Dino, strange phenomena indeed!--yes, that was a former hole, out of which Kennedy's brains blasted hard against the motorcycle cops to the left of the back of the limo!