Not a expert, but willing to give it a go
Pic # 1 ...could be a sharp feed ramp .. either going in or out
Pic 2 Your chamber is very rough .... I mean very rough ... I hope you do not reload
Pic 3 are you using metal mags or Plastic ???? more rough chamber
Stock barrel or mra barrel
Take a flash light and look at the chamber. The chamber is probably scratched all to ####.
Brass ejects at 3:30-4 o'clock and I've never seen this mark on buffer face so soon.
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