Grooves on the neck

[troutdiver]

I have a 10BA in 308. After I shoot the necks of the cases have grooves that almost look like rifling. The brass is trimmed to specs 2.005. Is there reason for concern?

[bigedp51]

Photos of the case necks would be helpful.

[RC20]

What is your case length.

What barrel is on the gun?

If its groves its extreme concern.

[Robinhood]

I have an HK that does that!

If they are "grooves" it could have been how the reamer was pulled from the finished chamber. How many?

[troutdiver]

They only happen when the case has been fired. If I chamber a new piece of brass it doesn't leave and marks.

[Deadshot2]

For issues like this I'm glad I have a Lyman Borecam. One of the best $229 investments I've ever made.

If a chamber is leaving marks on the fired brass about the only way to diagnose the issue is to look inside with borescope or borecam.


If it's a factory rifle under warranty they should "make it good". If it's a custom and this is happening from the start, the custom builder should make it good.

If it is a used rifle then it could well be why it was sold.

If the "grooves" aren't very deep I'd see if a gunsmith could polish the neck area of the chamber.

Last thought, I have heard that some H&K barrels caused this kind of marking on cases but never heard why.

[RC20]

They only happen when the case has been fired. If I chamber a new piece of brass it doesn't leave and marks.

If you reload, its a problem. One off and be sure to not let the brass into someone elses hands.

The case neck is not designed for that kind of impression.

At best on a reload it will split early and annealing will not stop.

It should not be there and it should not be doing that.

Why and HK does it is ? Europeans can be odd, some chambers stripe the whole case as they are only partly supported.

That is a case of a design purely for combat not reloads.

[RC20]

I have an HK that does that!

Caliber?

[Robinhood]

7.62

http://forums.pelicanparts.com/uploads24/hkbrass1448325347.jpg

[RC20]

Robinhood: What you have is a European design that focuses purely on working and care not about re-loading.

Ergo the marks, I know there is one on the (FAL?) that does that (may jut be HK, fizzy memory on that)

Basically they are minimizing the surface area that will grip the case. Ala easier extractions.

Different than having the marks on the case neck. in a normal barrel.

[Robinhood]

No doubt.

[Scott Evans]

That is a fluted chamber, HK was famous for it. Supposed to aid in extraction. In the case of the HK roller delayed action, extraction was aided by gas pressure via the flutes. WHY a bolt action has this is beyond me, but I'd want to stick with heavy NATO 7.62 cases. Seems like its a solution without a problem just to be more tacticool.

My bad, isn't OP's picture.

[Robinhood]

Sorry for pulling the OP's post off track. It is RC20's fault....I swear.

[RC20]

Sorry for pulling the OP's post off track. It is RC20's fault....I swear.

Well after having crawled out from under the bus.

Lets get back to the OPs issue?

[sharpshooter]

By any chance are you using a Lee collet die?

[Texas10]

It's fishing season. He'll be back when the river freezes over and then maybe we'll get a picture.

[bearcatrp]

Wow, never seen this before. Waiting on explanation as to why. My 1st thought was one hell of a hot load.

[Scott Evans]

If you are referring to the picture that is a case fired in an HK 91/G3 rifle. they all look like that, with carbon streaks, the chamber is fluted to aid extraction. They heat cases RED FRIGGIN HOT and throw them a long ways very fast in unpredictable directions. Don't ask how I know this ;)

That is NOT a picture of the OP's problem.