Traces on bullets PPU. Need your advices

During disassemble PPU cartridges I admitted some traces on its bullets. Need your advices. I need to know your opinions - how these traces appeared at these bullets? Did these traces appeared during disassembly or otherwise - during assembly bullet inside shell on PPU plant? Thanks a lot for your opinion which is really important for myself!

The case mouth inside diameter is a little less than the bullet outside diameter to ensure the case has a firm grip on the bullet.
If the inside of the case mouth is rough, the scratches shown are created when seating the bullet in the factory (or by a reloader). When pulling the bullet from the case, the scratches will be deepened a little, because the rough points inside the case mouth still exist.

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So. I disassembled these bullet from new cartridges. That means - these trases appeared during assemble cartridge on PPU plant? Did I understand your adwice right?

Yes, that is my opinion.

Thanks a lot.
I have the same opinion. And photo explain whythat%20why

Two other questions

  1. Is it possible that these traces stay on bullet after shooting? Or maybe surface of barrel channel shell erase them?
  2. Is it possible that these traces on a bullets from one box (or made in one plant line) matches during forensic comparison?

Your question 1 would have to be answered by a forensic expert, which I am not.

The answer to question 2 in my view is no. The scratches are created by the roughness patterns of individual case mouths. There is no guarantee that all cases in a given box were finished by the same die one after the other. Modern plant lines use multiple dies in parallel.
One would have to take a large number of cartridge boxes and compare the bullets from each box to find out how large the similarity of scratch pattern in a typical box is. This figure could vary considerably between mass produced calibers like .308 Winchester and calibers that are made in much smaller numbers. My recommendation is to examine cartridges of a popular caliber in a limited number of boxes to get a feel whether your approach might yield useful results.

Thanks a lot for your opinion. Nice that our opinions are same.
I disassembled a lot of cartridges and saw such scratches only on bullets of some brands. For example PPU (Serbia), Takho (Ukraine). All these cartridges are in low price category. Between more expansive cartridges I do not saw such scratches.