Help diagnose markings on spent cases and build of the week

[Dcommoncents]

Hey all, long time no post.

I am trying to figure out the cause of some dents/scratches that are being left on cases fired out of my 18" mlgs grendel upper. As you see in the picture, there is what appears to be a scratch around the neck and a dent on the body of these Hornady Black 123gr cases.
[ATTACH=CONFIG]13241[/ATTACH]

My guess is the scratch on the neck is caused by the feed ramps during feeding, while the dent on the body is from hitting the shell deflector. Any opinions as to the cause of these marks or what might be done to eliminate them?

Also, as an aside, I thought some of you might be interested in hearing that I successfully represented the short barreled Grendel world in The Firearms Blog's build of the week feature. https://www.thefirearmblog.com/blog/2018...t-results/

[A5BLASTER]

Try adjusting the gas or a heavier buffer and see if they still strike the shell deflector.

[VASCAR2]

The dents in the body of the brass is normal and is caused by hitting something solid like the deflector or the edge of the ejection port. Never seen the small dent cause a problem in my reloads of 6.5 Grendel. I really couldn’t see the radial scratchs in your pictures. New mags will put scratches on brass as will the lugs in the barrel extension where there close to the feeding cartridge. As the rifle and mags wears in the scratches tend to diminish to where there not noticeable.

Your brass looks normal to me maybe others will chime in.

[depletedyourcranium]

Scratch on the neck is easy to diagnose. Chamber a live round, eject manually and inspect. If the mark is there you know it doesn't happen during firing, extraction, or ejection.

[Dcommoncents]

Thanks for the comments. The dents on the body only appeared after my most recent outing with this rifle. I was thinking it might be an over gassing issue, so perhaps I put a lighter buffer in it and forgot, I'll have to double check.

I'll try to narrow down the cause of the neck scratches as suggested. If it is caused by the lugs during feeding, what do you suggest? Perhaps some light polishing on the corners of the bottom lugs?

[Kswhitetails]

Polishing wouldn't hurt either way. Check your mag lips. I'd bet those are a part of your issue here. Some polishing for both?

I don't see anything I'm all that concerned with, what bothers you about what I'm not seeing?

[65Whelen]

The dings on the body aren't unusual, heavier buffer might help. The dings on the neck are unusual, don't know what to say there, sorry. And, congrats on the build recognition. That is a nice build.

[Dcommoncents]

Thanks all. I've been using AA mags, and no scratches are left on brass fired from my grendel pistol, so I don't think that's the issue. I'm going to assume at least some of the issue is over gassing; will try a heavier buffer or adjustable gas block and report back if I learn anything.