Black soot build up on case heads

[beto]

place where?

Inside of tumbler.

 

[Jakeweb09]

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.

In my experience 26 is fairly dirty, but never had this happen. I got the gun from the smith with his proven load, started 1.5 grains back and worked up from there in .3 grain increments. I don't think it's to little powder. Charge started at 60g worked up to 61.8.

 

[Jakeweb09]

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

I don't have a gauge, but I will say that I bumped back 1thou after first firing and after this firing I remeasued and They grew another 2 thou past previous growth, making my previous bump 3 thou from this measurement. So maybe overbump is the whole issue

 

[Privi457]

Try factory ammo

 

[milo-2]

I don't have a gauge, but I will say that I bumped back 1thou after first firing and after this firing I remeasued and They grew another 2 thou past previous growth, making my previous bump 3 thou from this measurement. So maybe overbump is the whole issue

I really wish i had the answer here. Now i may get flamed for this, but believe ADG saum brass has a little more case capacity than original case design which could cause problems.
I had similar, or what I feel was similar in a 25 saum, using 6.5 adg brass. I was definitely getting blowback in my chamber, but not sooted case heads. And my problem started after I sized my cases for the first time, but my cases only grew .002", my bump was minimal. The only way i could shut it off was more powder, which pushed me way over 3200 fps, which I did not want.
My conclusion was adg saum brass was not for me. I shoot 7 saum also, and still have a stash of Rem brand brass from yrs ago.

 

[LRNut]

I don't have a gauge, but I will say that I bumped back 1thou after first firing and after this firing I remeasued and They grew another 2 thou past previous growth, making my previous bump 3 thou from this measurement. So maybe overbump is the whole issue

I have no idea how you can estimate you are bumping back .001 without measuring.

Shot in the dark, but are you using KG12 solvent? If so, any chance that is on the bolt face?

How loose are your primer pockets? Loose primer pockets will cause that issue.

 

[Jakeweb09]

I really wish i had the answer here. Now i may get flamed for this, but believe ADG saum brass has a little more case capacity than original case design which could cause problems.
I had similar, or what I feel was similar in a 25 saum, using 6.5 adg brass. I was definitely getting blowback in my chamber, but not sooted case heads. And my problem started after I sized my cases for the first time, but my cases only grew .002", my bump was minimal. The only way i could shut it off was more powder, which pushed me way over 3200 fps, which I did not want.
My conclusion was adg saum brass was not for me. I shoot 7 saum also, and still have a stash of Rem brand brass from yrs ago.

thats definitely interesting. As the proven load the smith gave me with the gun was a shade under what was working in my work up. Pretty sure he was using Norma brass so with ADG I expected the opposite. With the load he gave me though I am shooting the exact velocities he had. (Within 10fps). I will be pulling the firing pin before bumping back the brass and feeling how they chamber.

And to LRnut I've always loaded mellow rounds with unfired brass and then measured the shoulders. Similar to the way you would do it if sending brass to Redding for custom dies. However I think the brass didn't fully expand on first firing. New brass measured 1.6245 with the Hornady tool. Then first firing it all measured to 1.6265. Bumped back to 1.6255, and second firing it measured 1.6285. So it clearly expanded more the second firing. While gauges will probably be more accurate and I'm probably gonna order some tonight. I've had great success sizing .001 back from my fired cases. And the fired cases in my other rifles have always measured consistent. However I have always used Peterson brass and this is the first time with ADG, so maybe it's just harder brass and takes a bit more to stretch to full length?

 

[blueprairiedog]

I just switched to staball 6.5 loaded annealed brass for scoring targets and some extra rounds for sighters that were not annealed shot the match a second time and needed the extra rounds.while shooting I started seeing soot on the brass so just now I checked and had soot on most of the brass that wasn't annealed with the what I think is slow powder

 

[264MHC]

This is an interesting one. Not seeing any ejector marks and primers look fine to me. Not even seeing any soot on the outer edges of the primer pocket. You very well could have some copper solvent on the bolt face. Had a drop of boretech cu+2 escape the bore guide on on of my ar's and get in the chamber. Each of the 30 or so pieces of brass I fired that day had irregular discolorations on the sides. Of course your bolt would have been out during cleaning. Maybe some solvent dripped on it on the bench that you didn't notice?

 

[muleystalker]

I don't have a gauge, but I will say that I bumped back 1thou after first firing and after this firing I remeasued and They grew another 2 thou past previous growth, making my previous bump 3 thou from this measurement. So maybe overbump is the whole issue

If you don't have a gauge how do you know how much you bumped the case back?

 

[jdyoung]

If you don't have a gauge how do you know how much you bumped the case back?

I think the meaning is he doesn't have a traditional headspace gauge to measure the chamber. But from his writing, he seems to have a gauge such as a Hornady to measure cases base to datum.

 

[Jakeweb09]

I think the meaning is he doesn't have a traditional headspace gauge to measure the chamber. But from his writing, he seems to have a gauge such as a Hornady to measure cases base to datum.

Exactly. I'm saying I don't have a go no go gauge. But I do have a Hornady headspace Gauge and comparator

 

[oneeyejohn]

As flat as the primer looks in the picture, you have all the pressure that case will stand with that powder load. You might try backing off the powder load and see if that stops the problem.

 

[hunter0528]

how much pressure is needed to Deprime a case? If you have a single stage press and just a decapping die, use a trigger pull gauge or fish weight gauge and see how much weight is needed to decap. Then compare that to new once fired.

Just a thought