Ejector/Extractor Marks on Brass - Gun or Ammo Problem?

[Nic]

Hi All,
This is only my second post here, so please be nice to the FNG :)
I have a new AR build, and as I was shooting at the range I noticed that some (not all) of my spent brass had ejector/extractor swipes on the headstamp. I was under the impression that this was a sign of overpressure. However, I only saw that when firing Federal XM193, and not when firing PMC .223 55gr. Even then, I only saw marks on maybe a third of the Federal brass.
My upper's specifications are:
Henderson Defense Upper Receiver
Sabre Defence 16" M4 barrel, 5.56mm Chrome Lined (Carbine Gas)
MI Low-profile Gas Block
RRA Semi-Auto Bolt Carrier group
And I am shooting with an H2 buffer.

My questions are:
1) Seeing the extractor/ejector swipes on the brass, should I be concerned/panicked?

2) Am I correct to assume that since I'm seeing the marks on only the Federal and not the PMC, this is due to the ammunition and not the rifle?

3) Should I bother trying to fix/replace anything on my rifle?

Thanks for any help you can give me. I love this rifle setup, I'm just concerned seeing what I think are overpressure signs on my brass. Just want to be safe, and not blow up my rifle or anything...
-Nic

[markm]

1. not neccesarily

2. correct. PMC is a wimp load, and XM193 is a super hot load.

3. I doubt it. A Sabre barrel's chamber is likely just fine.

[Nic]

markm-
Thanks for the prompt reply. I forgot to ask one more question... would it be safe for me to continue using the XM193? Should I just go ahead and shoot it and not worry about it?
Thanks again,
Nic

[markm]

I can't say with 100% certainty. I've shot ammo that stamped the ejector and extractor cuts into the headstamp without issue.

It's probably alright, but with out seeing it in person I can't give a true opinion.