also from that site...
@ DNS
Femur shafts can suffer greenstick (aka spiral) fractures quite easily with the correct force.
Not to nitpick, but I feel you are a poster who has good information generally and this one needs to be rejigged.
A spiral fracture is not associated with or synonymous with a greenstick fracture. A greenstick fracture is an incomplete fracture of a paediatric bone. The reason it has that appearance is because of the difference in mineralisation between a kid's bones and an adult's. The kid's bones will have more 'give' and may bend on one side and suffer a compression deformity (or partial fracture) on the other. A spiral fracture is a complete 'break' through the bone but it has a significant extent on the long axis of the bone. The greenstick involves a narrower area (on the long axis of the bone).
@ All
As regards bones and gunshots:
1) A round with a low mass and velocity is more prone to deflection and failure to fracture a bone, all other things being equal.
2) The skull is a very complex target, primarily because of the bones of the face. These are complex both in terms of density and arrangement. These variables (even if you pretend to have multiple identical skulls) mean that deflections and failures to penetrate are not surprising with any service calibre load.
3) As DNS said, you get variation in terms of mineralisation, bone thickness, underlying metabolic disorders and overlying tissue variables. These all add up. If you have a look at a few CT scans through the same anatomical baseline on multiple patients, you will get variations that are easily appreciated.
4) The .22 is at a disadvantage in terms of mass and also its ability to retain mass (in other words it is prone to fragmentation because it has no jacket and is made from soft lead).
Here is some more for you to chew on:
If you guys have a serious interest in gunshot wounds you should read Vincent J.M. Di Maio's book 'Gunshot Wounds.'
http://www.amazon.com/gp/product/084...lance&n=283155
In Di Maio's book, Chapter 9 deals with 'Bloody Bodies and Bloody Scenes.'
Di Maio noted that of 185 cases of suicide by .22, only 20% of those bullets exited. Of 60 cases of homicide by .22 only 6.6% exited. These figures are from gunshot heads only. He further adds: "...of the bullets that do not exit the head, the vast majority are retained in the cranial cavity. Thus, internal ricochet is fairly common, occurring in anywhere from 10 to 15% of the cases..." (See page 264 and 265)
Also, you can give Malcolm Dodd's book 'Terminal Ballistics' a read:
http://www.amazon.com/gp/product/084...lance&n=283155
In Dodd's book, Chapter 8 deals with the 'Rimfire .22 Projectile.'
Dodd acknowledges that "...the .22 short and LR rounds also have the reputation of internal ricochet within the cranium, further creating complex injury patterns..." (See page 41)
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I've seen one or two gunshot wounds and I can tell you that even small projectiles can fracture heavy bone. In one case a .25ACP broke a guy's thumb and his femur. That's not bad for a mousegun. in another case a larger projectile (somewhere around .357) pancaked and deflected off a femur. Of course there are variables to do with clothing and range and the type of projectile, but the bottom line is that you can expect the unexpected.
Having said that, I would say that a .22 is low on my list of projectiles I would choose to penetrate heads. There are too many variables however, to dismiss it outright as not capable of doing it.
