Lesson Re-learned

[stanc]

A 5.56 behaves like an explosive round already, which may not be that effective on an under-nourished Muj fighter who burns his feces in the winter to stay warm. Say we gunned him down with 7.62x39, 7.62 NATO, 6.8, or a Grendel in the same close-range scenario. I doubt a different assault rifle caliber would have yielded a different result, honestly.

There's no way to know for certain without going back in time and having MSG Pryor do it with a different caliber.

However, as I understand it, such failures with M855 Ball result when yaw doesn't begin soon after impact. That can be caused by different factors (such as "fleet yaw" and angle of attack), which I don't remember well enough to explain, but which also reportedly 6.8 SPC is much less affected by. I don't know how 6.5 Grendel fares in this regard, but proper testing would show.

I think it's quite possible that a bigger, heavier (6.5 or 6.8mm) bullet would give superior terminal effectiveness than 5.56, and do it more consistently.