Marked And Gouged Brass

[SideShow Bob]

I finally got around to sorting my brass from the Sept. 8th Harris Park shoot, and noticed that on some of the bases of .458 SOCOM brass that there are marks or gouges to the point of making a burr.
It appears that the extractor is the cause, but when I cleaned the rifle that evening after shooting ,I didn't notice anything unusual.
I took a real close look at the bolt when I noticed the damaged brass and it appears to be fine.
Anybody have the same problem and or a possible cause and solution for this ?

See the attached pictures if my explanation is not very clear.

SSB.





Sent from my ass using re-fried beans.

[XC700116]

ejector mark and looks like slightly flattened primers would suggest a bit on the hot/high pressure side, not sure on the extractor gouging though.

[babirl]

Commercial rounds or your reloads?

Projectile, load and powder would be helpful. Also, what rifle/BCG... I'm guessing RRA?

As said before, it's pretty easy to get "hot" w/ a 458S, especially w/ the TTSX... I have a few cases showing nearly the exact same marks w/ some reloads and decided to back off until "we" learn more. Still working on "perfection" for multiple projectiles and the TTSX custom...

In the meantime, pretty sure a few feet-per-second isn't worth beating the hell out of your rifle or brass... Big Bore ARs are still awesome!


B2

HOWEVER, with my loads, I'm not convinced this isn't just an over-exuberant extractor that needs some break-in, a buffer change or some such thing... I CERTAINLY don't feel in danger.

[SideShow Bob]

Factory loads, 300 gr. hollow point, guessing Remington due to not being listed. Factory rated at 1950 FPS.
Yes, complete RRA carbine 16" upper.
Not all are gouged, I would say about 12 out of 100. And about 30 have a light rectangular impression. The rest, 58 are completely unmarked.

Could there have been an obstruction causing the extractor to cause this ? I disassembled the bolt and didn't see anything while cleaning, but that was before sorting all the brass from that range trip.

[Jherexx]

Just read an article recently in Rifle Magazine on the Remington 30 AR that had the same problem, they called it Case Head Sweep. The article mentioned it's a sign of mild overpressure and that the loads are not tuned to the gas system of the rifle. If I remember correctly it has something to do with timing between when the bolt unlocks and the brass expands/contracts after firing.

[jerrymrc]

Just read an article recently in Rifle Magazine on the Remington 30 AR that had the same problem, they called it Case Head Sweep. The article mentioned it's a sign of mild overpressure and that the loads are not tuned to the gas system of the rifle. If I remember correctly it has something to do with timing between when the bolt unlocks and the brass expands/contracts after firing.

Normally when you have a timing issue it is because the brass has not contracted enough and you see pull marks on the rim. I deal with this a lot in my world but it is easy to fix with a piston system.