The 22lr has a nasty habit of being easily deflected.For example Pres Reagan was shot with one It went into the chest cavity , hit a rib and bounced back and punctured his lung.Autopsies of those shot with a 22 are difficult because the bullet , after entering , can be almost anywhere.
There is nothing unique about the characteristic of being deflected off of bone and ending up somewhere else other than on the original entry trajectory. It happens with every caliber. If a twig can deflect a .308 sniper's shot, then nobody should be surprised that a bone could deflect a .22 lr inside the body (and any other round).
People seem to like to mention this deflection issue as if the deflection of a bullet somehow makes it more lethal. People talk about .22 lr rounds bouncing around inside the chest cavity and inside the cranium. In terms of the chest cavity and body, "bouncing" around can just as easily result in being deflected away from vital structures as being deflected into vital structures. In fact, if you are aiming at a vital zone, then deflection can be the absolutely worst thing that can happen to your shot.
So how about all this bouncing around? One almost gets the impression that a .22 lr round gains momentum with deflection as if a deflected round travels further and can hit more organs than a round that isn't deflected. Nothing could be further from the truth. Deflection is detrimental to the bullet's penetrative abilities as energy is tranferred from the bullet to the bone when the bone changes the trajectory of the bullet.
The bullet that hit Reagan was indeed deflected, but it only had 6" of travel inside the body (3 before and 3 after deflection). Had the entry trajectory been different, the round very well may have been deflected out of the body as easily as into the body.
Note that the .22 lr round that hit Brady did not bounce around inside the skull.
A .22 lr round may indeed deflect off of bones. This can and does happen with all calibers. However, the notion of "bouncing around," is just silly. While possible, it would be the rarer exception for a round to "bounce" more than once off of bones, but "bouncing around" implies that it happens and apparently with quite some regularity. That simply isn't the case with .22 lr or any other caliber.
As for the effectiveness of the .22 lr througout history, causing deaths does not indicate effictiveness. Nasopharyngitis kills nearly 1000 people a year (known) and has been around probably as long as people have. However, the long history of deaths is meaningless in regard to it being effective. In the US alone, nasopharyngitis results in 75-100 million doctor's visits. Sure, it can be lethal, but lethality is extremely rare. .22 lr can be lethal as well, but a lot more people walk (not carried) into emergency rooms with .22 lr gunshot rooms than probably any other caliber. Reagan did.