Guess they wanted a bit more power to their rifle rounds, although a 22LR will do the job if you aim it right. If you're just aiming anywhere or in a particularly well padded area, you might want to up your round power. For small game, a 22LR is all you need, for larger animals, you might want to go up in size.
If it's for self-defense, well a 22LR will do for anyone able to place a good shot; in fact I remember an old story told to me by bunch of doctors, who claimed in terms of internal damage to head and enclosed cavity inside of a body, the 22LR did far more gruesome damage that was visible, because the round would bounce around and turn anything inside into mush, since the energy of the bullet wasn't enough to exit out the back and would constantly ricochet inside the skull or bones. Needless to say, the images they showed were horrifying.
What's so bad with 22.lr? Did the character wish for it to be 22.magnum or hornet maybe?
She's just a caliber queen per the artist's other posts.
Kumihou said:
If it's for self-defense, well a 22LR will do for anyone able to place a good shot...
If you have any choice in the matter, do not use .22LR for self-defense applications. Rimfire primers tend to be less reliable than centerfire ones, and you don't want to be in a position where your gun won't go bang in the split second you desperately need it to.
As for the internal damage, the stories about .22LR bouncing inside the body are probably exaggerations of stories told about an alleged assassination technique, where you press the muzzle of the .22LR gun against a specific part of the head so that the bullet will enter the skull but won't leave it, causing major damage inside. I don't think this is applicable to the effects of .22LR generally, given the kinetic energies involved will likely dissipate too quickly.
If anything, that 5.45x39mm might be better if you're looking for "more internal damage than the ammunition would imply at first glance", as certain patterns of that ammo are known for unstable terminal ballistics resulting in tumbling inside the flesh.