[Trailerpark Badass]

Well, in an AR cases frequently get scratched by sharp edges on the barrel extension locking lugs, the edge of the ejection port, the case deflector (when present).

So figuring out which scratches are from the mag would seem to be a fool's errand.

Just looks like busy work for criminal justice majors from online universities.

[Scrambler Bob]

Yes, and what would such a report look like:

Little J__ was hit in the ‘x’ with the first round, from the first magazine. Then the second round hit little S__ in the ‘y’ and the third round ...

And comments about how much damage each bullet did, and internal injuries, and suffering, and who (surmised) saw whom die before them, and off into emotional speculation, giving more fodder to refresh the bored audience against ARs, at some later time when needed.