.223 will not blow through an engine block. Not even with a FMJ. Oil pan, maybe. We trained at a junkyard all the time and left us all pretty humbled. Found that 75% of the 9mm rounds wouldnt even penetrate a friggin windshield, it deflected because of the angle.

We tried the "engine block" test with .223 and .308- neither worked.

But, with that said, I personally know a rancher that killed (legally) 21 elk with a 22-250, one shot apiece. If you extensively injure an animals lungs, he will always die. Every time.

Just my .02