Will the .22 LR take-out game that you wouldn't think it capable of doing so; sure OK, it will and has done so for a century and a half. Will it shoot through an animal's skull? Yes, many critters have a thin enough skulls for the .22 LR to compromise it at close range.
Question is, should you task it to do so? No, probably not.
Poachers have used the .22 LR for one and a half centuries. Do professional assassins trust it for wet jobs? No. Two reasons,
1) insufficient penetrative energy (especially against thick portions of the skull; example,the occipital bone protuberance);
2) the .22 LR is a rim-fire and therefore is not a
100 percent certain ignition (used to, firearms manufacturers used TWO firing pins for rim-fires to attempt to more certainly ensure ignition). I've been shooting firearms well over a half-century / gone through tens of thousands+ of rounds of ammunition. I've had many misfires with .22 LR cartridges, but NOT with center-fire ammo. Center-fire ammo fired in quality firearms ignites. Wet-jobs require ultimate certainty -- poaching animals, not so much. Assassins used to begin with the .32 -- the .32 automatic, most often. They needed >= 60 grain bullets with which to begin -- absolute bare minimum. Most all .32 automatics have fixed barrels, thus are much easier to affix silencers and get profoundly few jams, if any. "Back in the day",
THE silencers to obtain were contracted/built through a crew of Chicago police detectives via the black market (connections required). (In the "for what it's worth" department, the KKK used to have its central power located in the Atlanta police department's detective division.)
So, YES, the "lowly" .22 LR is far more lethal than the
hoi polloi give it credit; yet, professionals go with heavier bullets fired from center-fire weapons. The men of my grandfathers' generation (born around 1900), gave a lot of credit to center-fire
.32 caliber rifles and handguns (this is a whole other topic, way too large a topic to pursue in this string) ... i.e. NOT the .22 long / .22 LR rim-fire.
Do I love the .22 LR cartridge? Yes, most definitely so.
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