Well you definitely have more relevant experience than me. My ship fired Tomahawks for Operation Enduring Freedom from the safety of being below the ocean. We did have M-16’s but the only thing we shot with those were boxes with shark mouths drawn on them when we surfaced for swim calls.
That said, you do bring up what I was getting at: grains, muzzle velocity and energy. Sure the .22LR and .223 are the same diameter, but the typical .223 bullet is about 50% heavier, travels at twice the speed and has nearly ten times the energy. I mean, would you say a .50 BMG is “basically a souped up” .50 AE? They’re the same caliber, right?
Anyway, I don’t see that guy’s melon taking a point blank hit from a .223, and the the bullet not blasting out the other side of it. Or if it didn’t blast out, then I don’t see him living long enough to let out all those whimpers after the bullet rolled around inside his cranium.
We had a guy get shot in the head with a 7.62x39. The bullet didn't fully penetrate the skull, but skipped up and into his kevlar, and then rode the curvature of his skull and out the back. Crazy things happen.
Anyhow, shipmate - I never made it to OEF; spent it all in OIF.
Semper.