I did something real simple which I'm sure a lot smarter people have done before me, which anyone with a ruler can do - I actually took the time to measure the size of the hole against the ruler in the photo.
I tried it in 2 different directions, and I got the following results: about 6.5 sixteenths and about 6.6 sixteenths of an inch.
So a quick poke at the calculator gave me a rough size for the hole of between .406 inch and .413 inch.
Or, when I converted that to millimeters, that would make the hole roughly between 10.3 millimeters and 10.5 millimeters.
I found a place on the web where it says a bullet hole can be a little bit larger or smaller than the actual caliber. I also found one of the actual experts talking about this case, who had said the hole didn't look like a hole from a .45, but more like from a .40 caliber or a 10mm gun.
So then I looked out on the web for some info about these calibers and I found a couple of interesting tidbits -
"During 1990, the 10mm Auto gained even more credibility as a self defense cartridge when the FBI abandoned the 9mm Parabellum and officially adopted the larger caliber. Other law enforcement agencies are sure to follow suit."
And more recently: "All FBI agents are issued service weapons upon graduation from the FBI academy at Quantico, Va. -- currently Glock .40-caliber semiautomatic pistols -- and many agents have several weapons issued to them, officials said."
Obviously, 10 mm and .40 caliber are real close in size. I don't know what other agencies might use one or the other of these calibers, but it's obvious that guns that fire bullets the size of the hole in Ron Brown's head are used by some agencies of the U.S. government.
All of which leads us right back to suspecting what we already suspected - that the hole was not likely made by a flying umbrella.
So will we ever find out the complete story? It would be nice, but my guess is, probably about as much as we know the whole story on Kennedy.
The roundness of the hole indicates high speed impact, much higher speed than objects which fly from a plane crash. "Must have been a rivet," was a buzz word tossed at Coggswell. But it was a low speed crash to boot. No way could a rivet have done that from a low speed crash.