New barrel first three rounds look at this brass

[Bretandry]

Brand new barrel these are the first three rounds and the brass shows these ridges and you can feel them EASILY with a fingernail.
My first instinct is to say this chamber is CRAP they spec to the same length as brass fired from another Grendel with a Hornady case comparator my other brass never showed this kind of damage from firing. Wondering what folks with more time and experience think.
Any help is appreciated 20220701_165407.jpg

[myrifle]

It looks like reamer chatter to me.

Either way I would be getting rid of that barrel. But I'm also a but of a barrel snob.

[Bretandry]

I had this upper built and asked the builder to send me the test brass..Glad I did these are those rounds... I won't be firing it I am sending it back as soon as he gets back to me. Chatter is exactly what I thought too. The guy is very reputable from all indications and I believe he will make it right. My big concern is for reloading that this condition would A) cause excessive brass fouling in the chamber and B) Cause me to shitcan brass before it's useful life span

[Klem]

Bret,

They look identical - four ridges on each case. Looks like brass has splayed under pressure into four machined channels. If this is the reason then you will be able to see or feel the channels with a paper clip.

It is probably a quality control issue by the manufacturer. Maybe swarf wasn't cleaned out as the reamer cut. It could also be the channels from four earlier case separations. If it is case separation then that means it has been previously fired. Case separations cut permanent trenches that size, but tend to happen lower on the case.

Who's the manufacturer?

[jasper2408]

Know anybody with a borescope? Then you could see exactly what the inside of the chamber looks like.

[Bretandry]

Klem.....Cases are Hornady I asked for new fired brass from test firing so i could see where the new chamber fireforming was for reloading purposes then well I inspected them when it arrived today and saw this. My uneducated opinion is that it needs to be replaced if for no other reason than it will bother the hell out of me....lol

[Bretandry]

No I need one Jasper you are correct.

[Zeneffect]

Replace, buy a borescope during the down time. I wouldn't accept that chamber.

[sundowner]

Had a chamber like that , I ran a chamber hone in it 6 strokes and the chamber was good , shots sub 1" groups at 100 yards .

[Klem]

Sundowner,

In your case was it ridges or trenches (these are trenches)? I ask because if you machine the chamber wider so that you can't see the four trenches anymore then you've widened the chamber and messed with the headspace.

[StoneHendge]

I had this upper built and asked the builder to send me the test brass..Glad I did these are those rounds... I won't be firing it I am sending it back as soon as he gets back to me. Chatter is exactly what I thought too. The guy is very reputable from all indications and I believe he will make it right. My big concern is for reloading that this condition would A) cause excessive brass fouling in the chamber and B) Cause me to shitcan brass before it's useful life span

Reputable builder who test fires.....

Care to divulge?

[Bretandry]

Stonehenge ....Only after I speak to the man on Tue because of the 4th.......an unsatisfactory conversation would result in my not being so happy....then yes...I would rather come back and let you all know the guy was a good dealer and made it right and help a guy rather than hit him before he gets the chance.

[sundowner]

Small ridges and did not run the hone all the way in , were at the bottom part of the case .

[Klem]

Small ridges and did not run the hone all the way in , were at the bottom part of the case .

That makes sense, thanks.

[BluntForceTrauma]

Had a batch of barrels where some exhibited similar "striations" as I called them. Manufacturer agreed cause was probably reamer chatter. Solution was a quick polishing of the chambers with a ball-hone like this Flex-Hone or similar.

We considered it a manufacturer's defect, even if cosmetic and not functional, and covered under warranty. Brass should come out clean and smooth.

Don't know if that's your problem in this case, but sure looks very similar.