I am not an expert. My cousin is married to a pathologist. That's my only "inside" or "expert" information.
My understanding is that newer hollowpoints are not as dependent on velocity, as evidenced by some of the gelatin testing.
My cousin's husband is basically of the opinion that you cannot really tell from terminal effect. As one of the earlier posts mentioned, the various service cartridges make similar wounds to the naked eye. My cousin's husband explains it like this. For example, they find a lump of lead/jacketing. Then they weigh it, measure the entrance/exit wounds, and guess it is a .355-357" cartridge, or whatever. Usually, you can't tell whether it is a 9mm, .38. or .357 in that example, assuming you are even that certain. Specific findings are usually dependent on ballistics. Sometimes it's pretty obvious it is a .38, since only lead is recovered (again, using this example).
He carries a 9mm with 124 gr +P or the Winchester 127 gr +P+ loadings. Now, so do I. His idea is that the 147 gr. loadings are good on paper, but they don't offer much insurance in extra velocity. He calims that their lab finds too many JHPs "plugged" with fat, subcutaneous tissue, clothing, or bizzare debris (like glass and steel fragments from a bag of groceries).
Just passing along my reasoning...
EDIT: The groceries thing is actually kind of interesting. A woman was shot with a stray 9mm bullet, but it passed through a bag of groceries first. She didn't die, so this is all hearsay (he is a pathologist, not a surgeon). The bullet hit something in a glass bottle, and began to expand. Apparently the partially expanded bullet continued to travel at relatively high speed, but it began to yaw wide right. It punched through a can and hit the victim's stomach. Apparently, this caused a really large, nasty, but superficial wound. According to this story, the ER surgeon recovered glass, steel, and groceries from the wound; the bullet was plugged with steel from the can. This was in Philadelphia a few years ago, if anyone can find a reference.