[Scrambler Bob]

“How do you “trace” a cartridge case “back” to a magazine?”

The only possibility I see is that the magazine lips on each magazine are microscopically different, and would leave unique scratches on each case.

That would be hard to analyze. Add the complexity that sequential rounds feed from alternate sides of these magazines. And perhaps the cases were scratched from some other source somewhere in their life. So my gut is that this type of analysis is useless. (But look at the process anyhow to eliminate it.)

And then which magazines were used in what order? This would confound things further.

Why? Agree with lots of govt work and long report.

Are they really trying to match magazines to cartridge cases, or is this just a failure to correctly communicate what they are trying to match with what.

[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.