I think everything you said generally supports my hypothesis. Nothing in it suggests that the round you discussed would break apart in a human skull at 10 FEET! And surely not without enormous pressures within the brain cavity, resulting in blood from the orifices in the head.
The victim only bled from the entry wound with some slight bleeding from the left nostril.
Can’t make that square with any shot from any AR round from 10 feet. Excluding a .22LR conversion of some type.
“I think everything you said generally supports my hypothesis. Nothing in it suggests that the round you discussed would break apart in a human skull at 10 FEET!...”
Without obtaining more information about the nature and composition of the bullet, analytic and forensic science can only carry this so far.
There are 22 centerfire bullets constructed of materials so soft and light that they fragment from air resistance, if driven too quickly from the muzzle. Disintegration threshold velocity is within the capabilities of the 223 Rem cartridge. What would happen if such a bullet (necessarily at a lower velocity) impacted the “average” human skull, begs additional layers of speculation.
And I have witnessed animals in the field, hit in the skull at short ranges (30 to 50 ft) with 22 centerfire bullets of various construction. Explosive fragmentation was nil; skull size was between that of a prairie dog and that of a human.
I must reiterate the probabilistic nature of impact results. Applied science (even when all evidence has been collected, accounted for, and correlated) can help but some uncertainties will remain, in any situation. 13 years as a scientific analyst for DoD taught me that attorneys and analysts inhabit different worlds, and never the twain shall meet.