Black soot build up on case heads

[IHFarmer07]

What coating is on the bolt face? Is it oily?

Also, is the bolt face coated with some sort of coating like dlc or something similar that may be coming off on to the case head?

 

[Muley hunter]

Anyone ever get it? And what causes it? I've been getting decent build up on some cases but not all. Tried multiple primers and same thing. It's happening on a 7 Saum with ADG brass and reloader 26.

I experienced this with Remington brass in my 7mm-08, particularly with factory Remington loads I had, and was using to fire form. Interesting in that I did not see this with Winchester brass to the same degree. The issue all but disappeared in the win brass when I switched over to Lee Collet dies. It is less apparent in my loads with Varget and H4350, but still shows up with R15 loads. After 1 reload (!), the Remington brass felt like very loose primer pockets, so I discarded them.

 

[Bob Wright]

Check the bolt face for etching. Then measure your primer pockets for size with a guage pin (thats how I cull brass)
If you ran a uniformer in your pockets, does your primer seat the same with resistance?
If yours is large rifle primed, here are some measurements from SAAMI.
I'm assuming you don't have Cerracote on the bolt face, which could transfer the cartridge...

 

[bubbaonpc]

Lil more powder...I had same thing working up loads. I first noticed LOW velocity on chrono...then I saw the soot...case was not sealing off and gas coming back. Increase powder...slowly and see if that doesn't cure issue...that is as long as there are no visible pressure signs...may be something else, but POWDER is my guesstimation

 

[Huntz]

Check your headspace with a go or no go gauge.

 

[milo-2]

Check your headspace with a go or no go gauge.

Yes ^^^^. Primer was flat, and I think overbump.

 

[kfreeze]

It looks to me, as was stated earlier, that it is probably coming from the bolt face. If the case wasnt sealing there would be soot all the way from the top down. When a primer is pushed hard enough to leak, it's been painfully obvious that it came from the primer. What you have almost looks like copper solvent on the bolt face. That stuff discolors brass and makes it look like that when it gets on it. Or possibly as others said some of the finish got on there?

 

[milo-2]

It looks to me, as was stated earlier, that it is probably coming from the bolt face. If the case wasnt sealing there would be soot all the way from the top down. When a primer is pushed hard enough to leak, it's been painfully obvious that it came from the primer. What you have almost looks like copper solvent on the bolt face. That stuff discolors brass and makes it look like that when it gets on it. Or possibly as others said some of the finish got on there?

I wouldn't rule that out, but given the fact Stiller bolts are nitrided, i guess I may be upset if mine got coated.

 

[wonderman4]

ADG treats their case heads to be harder than most other brass. They do this purposely for the reloader to prevent primer premature pocket expansion.

In my experience, with an inappropriate load, this would cause the problem that you are having.

You have never stated your powder charge, so I am speculating that you need to increase the charge in order to increase pressure to seal the chamber. Providing that you are not close to published max load. If you are at max load, then start over with a faster powder.

 

[Rick Richard]

Try a different case brand if possible and see if the issue is still there. Just a thought.

 

[Gone Ballistic]

I had a similar problem with a 30-338. After checking everything possible with the case, primer pockets and primers, neck thickness I finally got my hands on a go-no go and found a problem with head space. Last thing I would have ever expected on a new rifle build, but it can happen.

 

[StumpGrinder]

Anyone ever get it? And what causes it? I've been getting decent build up on some cases but not all. Tried multiple primers and same thing. It's happening on a 7 Saum with ADG brass and reloader 26.

I have never used that powder but some powders burn cleaner than others. I usually get powder residue on the case mouth with necked cases because of where they seal when fired. If powder residue is getting clear back to the bolt face either the case is not sealing in the chamber due to low pressure or the primer pocket is leaking. The primer should have stiff resistance when seating. I use varget and the new copper removing powders. I also find the cases come out cleaner and my loads more accurate when I load near max. When working up a load I approach max at 1/2 grain incrimints till the primer showes signs of flattening or max accuracy opens up. If primer starts to flatten first I back of 1/2 to 1 grain. If this only happens on 1 or 2 cases check for hair line cracks in the case body.

 

[beto]

Anyone ever get it? And what causes it? I've been getting decent build up on some cases but not all. Tried multiple primers and same thing. It's happening on a 7 Saum with ADG brass and reloader 26.

Place a couple of used dryer sheets. Works for me.

 

[Jakeweb09]

Place a couple of used dryer sheets. Works for me.

place where?