What is the cause of this?

[dfanonymous]

I'm just going to take this slow and answer any questions to help trouble shoot this..I've very curious.
So there is this black soot on my necks and these cases get stuck in the chamber..however if i take a cleaning rod i can just touch the case and it pops out..not hitting or pushing required. No sticky bolt. I've cleaned the rifle, so its definitely the handloads.
Using H1000 and 212gr ELDx with Federal brass. Remington LA
These all ranged from 69gr to 71.2gr. Pressure is up there but I wouldn't call it excessive. Bullet seated to mag length and verified not on the lands.
shoulders bumped back .002/3
primers: large rifle cci br2
necked trimmed to COL 2.620
NOT annealed.

Any ideas about the soot and the stuck cases?

 

[dok7mm]

I noticed this on a 7RUM couple years ago. If I remember right I increased neck tension and upped powder charge. Solved the problem, but it wasn't my rifle and I didn't retain any records. I do remember the powder on the case sure got my attention. The owner is shooting 3" groups at 600 yds, with that recipe last I heard.

 

[dfanonymous]

Ill have to look at the neck tension, but measuring it, its right where it needs to be..the highest charge i went was 75.5 and is pushing a 212 eldx at 2870...which is pretty up there? When it got stuck, i popped it out and I didnt notice any pressure signs however...just flying out fast. I just assumed it was time to stop and go down. best groups where at 72.2gr. But now those are getting stuck too.
Haven't noticed this black soot until i started using unique case lube...which i tumble..off or so i think...

 

[Deleted member 46119]

The case max length/chamber limit is 2.620. The book trim to length is 2.610

Are you sure you still have about .010 chamber neck length left? That you not are binding on the chamber mouth? A case trimmed to 2.620 should be just touching the champfer. The machining dimentions are 2.620 +.005.

Trim a case to 2.615 or 2.610 and see if the problem goes away.

A couple more questions.

Did you neck turn?

Is it a tight neck chamber?

If the brass is not annealed, a little residue, heat and stretch to yield=lightly stuck case.

 

[dfanonymous]

The case max length/chamber limit is 2.620. The book trim to length is 2.610

Are you sure you still have about .010 chamber neck length left? That you not are binding on the chamber mouth? A case trimmed to 2.620 should be just touching the champfer. The machining dimentions are 2.620 +.005.

Trim a case to 2.615 or 2.610 and see if the problem goes away.

A couple more questions.

Did you neck turn?

Is it a tight neck chamber?

If the brass is not annealed, a little residue, heat and stretch to yield=lightly stuck case.

This is good...
No, not a 100% I put the cases in the chamber and closed the bolt to check for any resistance...there appeared to be none..but I will trim them down further, and give it a go.

No I have not turned the necks...
It is not a tight chamber however.

 

[Deleted member 46119]

This is good...
No, not a 100% I put the cases in the chamber and closed the bolt to check for any resistance...there appeared to be none..but I will trim them down further, and give it a go.

No I have not turned the necks...
It is not a tight chamber however.

Yes then look to slightly long necks. Trim them back.

Been there done that.

 

[dfanonymous]

Yes then look to slightly long necks. Trim them back.

Been there done that.

Will do, also i just uploaded in the OP some pics of the brass.

 

[Deleted member 46119]

Will do, also i just uploaded in the OP some pics of the brass.

That looks like what I described.

 

[dok7mm]

That looks like what I described.

Either length or residual lube in this situation rings true.

 

[Trnelson]

You will also want to clean the chamber as it likely has a mirror image of residue on it.

 

[velvetant]

If your cases come out that easy maybe you need a new extractor

 

[Reloader222]

The fact that the black soot goes on the shoulder could be a sign of low pressure when the bullet exit the case. This could be caused by seating the bullet too far out. The rule is usually to have at least caliber length inside the neck. So if you load for 7mm Rem Mag then you should have at least 0.284 inside the case neck. Also take in consideration that boat tail bullets have less bearing surface inside the case neck compare to a flat base bullet.

 

[dfanonymous]

Ok. Loaded up 20 rounds today, and went to the range and shot them. I trimmed from 2.62 to 2.15. Used 71.2 gr of H1000. I cleaned behind the extractor. Used a spray on case lube instead of unique. Everything else was the usual for me. No sizing deviation.
Results:
No failure to extract. Not a single one. The soot was...a tiny there there but not even close to how bad it was before. I feel maybe if i go to 2.610 like the lyman manual said to that it will be groovy. Obviously it changed my poi and results from the last work ups...but that was expected.

 

[rharfo]

I'm having the exact same issue. Shot my 7mm Dakota today and the cases are black at the neck. Haven't measured yet but guessing I'm gonna have to trim.