The other day I watched a show in which one character was standing near several others, and was shot with a pistol in the back of the head.
Kind of a gruesome question, but can you presume that a shot to the skull will continue along a straight path? At least if it was a small caliber, might it be possible that the bullet would ricochet off the inside of the skull, and exit to the side - or even back the way it entered? If it did, might it strike a bystander, or even the shooter?
Moderating
Edited title to indicate the presumed meaning of your abbreviation (and not Golden State Warriors, which was the first hit).
If that is not what you meant, let me know. Please write out abbreviations that are not immediately obvious.
Colibri
General Questions Moderator
One thing you need to consider is the type of bullet. For example the hollow-point bullet:
No, I don’t think you can presume that. Gunshots regularly ricochet off people’s skulls or inside of them. And yes, they can go all sorts of different directions, even back the way they came.
My friends in organized crime tell me that the .22 is favored for executions, because a head shot will often result in the smaller caliber bullet bouncing around inside the cranial cavity and doing more damage than a straight-through shot with a higher caliber round.
“Richie loved to use 22s because the bullets are small and they don’t come out the other end like a 45, see, a 45 will blow a barn door out the back of your head and there’s a lot of dry cleaning involved, but a 22 will just rattle around like Pac-Man until you’re dead.”
While a .22 bullet will be deflected more than a heavier bullet simply because of its lower mass, the part about it bouncing around the cranial cavity is a bit of a myth.
A good example of what usually happens is the attempted assassination of President Reagan in 1981 with a .22 revolver. The bullet that hit James Brady did not bounce all around inside of his skull. The bullet definitely did some damage and the poor guy was in a wheelchair for the rest of his life, but the bullet did not bounce all around like the myth says. From the diagrams that were released to the press, the path of the bullet was fairly straight, entering the skull just over his left eye and heading roughly towards the area above his right ear.
The bouncing bullet is a very common myth though, and shows up in so many books, movies, and TV shows that many people just accept it as fact. I’m honestly not surprised that even someone in organized crime would believe it.
Autopsied many gunshot-to-the-head victims? If so, what did you find regarding internal ricochets or lack thereof? I figure you should have more experience being inside people’s heads than most mobsters, or even psychiatrists. 
The .22 bullet that hit Reagan bounced off the inside surfaces of Reagan’s ribs, at least twice, IIRC.
This military rifle bullet obviously fragments and veers off at an angle, even without hitting any bones. The US 7.62 x 51mm FMJ bullet, on the other hand, seems to continue on its path despite tumbling by 180 degrees as it goes.
Sorry about any confusion. I guess I watch too many crappy cop shows on TV. My wife and I regularly joke about how the spoken abbreviation GSW actually uses nearly twice as many syllables as the words. 
The bullet that hit Reagan ricocheted off of the limo door, deflected downward off of Reagan’s rib, and lodged in his lower lung. There were no multiple ricochets off of Reagan’s ribs.
Getting more than one bounce is possible. It’s just nowhere near as common as the myth indicates.
Another quirk of the Reagan assassination attempt is that the bullets Hinkley used did not function as designed. Hinkley used “Devastator” bullets, which were ordinary. 22 Long Rifle lead bullets, but which had a small aluminum cavity in the nose of the projectile. The cavity had a small amount of lead azide, an explosive compound used in firearm cartridge primers. The intent was for the explosive to detonate upon impact, causing a violent shallow wound, and avoiding overpenetration. The bullets were marketed to law enforcement use.
None of Hinkley’s bullets exploded, AFAIK, though it was a concern for medical personnel at the time, who were trying to remove one of Hinckley’s bullets from DC Officer Delahanty. See, https://www.upi.com/Archives/1981/04/03/The-FBI-today-examined-the-22-caliber-bullets-that-wounded/2543355122000/ for a 1981 article looking into the issue.
.22 LR solid bullets penetrate well compared to expanding handgun bullets. Where they lack penetration isn’t necessarily due to their low mass, but their low sectional density, which is their mass divided by their diameter. Thin, heavy fast stuff, that doesn’t fragment or upset, penetrates further than slow, wide, light stuff, all else remaining equal.
Aside, the magic bullet from the Kennedy Assassination, a 162 grain, 6.5 mm round nose bullet, has a gigantic sectional density. While it was not going fast as centerfire rifle bullets typically go, it’s slow velocity also meant it was much less likely to fragment while going through flesh than a faster bullet. Hence the great amount of penetration it achieved.
As to the OP, rereading my copy of DiMaio’s Gunshot Wounds, I didn’t find where the author noted any propensity of the .22 LR bullet from a handgun, to unduly ricochet within the cranial vault. Often, the bullets exited the cranial vault, and occasionally were retained by the distal layers of skin. Skin is quite tough and elastic. He did note that the bullets frequently left lead shavings behind in tissue, even if the bullet itself exited. All of this is covered in the section of the above work devoted to wounds caused by .22 bullets.
A lot of the terminal ballistics behavior of rifle bullets depends on the velocity with which they hit. Faster bullets will fragment more readily than slower ones. Different types of ammunition will fragment at different speeds. The net effect is that ammunition can have widely varying ranges at which it will fragment, depending on the type of bullet, and the muzzle velocity of the projectile.
855 is a special case in that, due to variations in manufacturing, different lots of it would yaw at different depths within tissue. The bullet would not start to fragment until it sufficiently yawed enough to subject the bullet to enough shear force. When this yaw doesn’t occur until 20 cm deep, and the target shallower than that, the bullet doesn’t fragment and the wound is much narrower.
Also, take a look at the 7.62 x 39 123 grain Soviet bullet wound path. It is known for taking very divergent paths through ballistics gel, and tissue. http://3.bp.blogspot.com/-D_PLHUYbKMk/UsbrnrHrtuI/AAAAAAAAAbQ/GC2BoxtzQro/s400/RussianWP.jpg
