Lots of soot on spent cases

[Shankedit]

I've got a large platform AR chambered in 6.5 Creedmoor and I'm getting a lot of soot from my reloads. Factory Remington green box (140gr core-lokt) look just fine - and they shoot unbelievably great out of it. Anyway, I've been using H4350 with 130 gr ELDMs and even at 42.3 grains of H4350 (close to book max), I'm still getting the soot. I'm not shooting suppressed at all, so that's not part of the equation. The photo of the brass shows the factory Remington (4 on left) and my reloads and you can see how much of a difference there is, and some of the cases are worse than these four. I'm not getting any signs of pressure with either the factory or my near-max handloads.
I'm guessing I'm either not building enough pressure and the chamber isn't sealing quite good enough before unlocking or the bolt is unlocking early. I'm thinking it's not building enough pressure because I would think it would unlock early on both the factory and reloaded ammo? I'm just not sure so I wanted to ask those of you with more experience. The brass ejects between 3-4 o'clock, so I'm assuming I'm in the window for being properly gassed.
What are your thoughts? Try a different (faster) powder? Heavier buffer? I tried searching the forum for an answer but I couldn't quite find what I was looking for, so I apologize if this has been discussed before.
Here are the build specs.

Aero Precision upper (M5 enhanced) and lower receiver (and handguard)
Bartlein barrel 400MODBB, (.936" at the gas block) 7.7 twist @ 24" with a rifle +3" gas system by Craddock Precision
JP Enterprises HP bolt headspaced to the barrel during chamber cutting
Aero Precision bolt carrier (nitrided)
Standard, non-adjustable gas block
Aero Precision rifle buffer tube with standard buffer weight and spring.
Aero precision lower parts kit
TriggerTech Diamond

Thanks for the help!

 

[ARlife4me]

if it's ejecting at 1-2:30 it's because of being overgassed. seeing you have aero receivers you should've stayed with their barrels. i speak from experience that their 6.5creed barrel w/standard rifle length gas system is perfect! on my 22" i don't even use an agb and/or an h1-h2 buffer. no brass issues or ejection marks. seams to be unlocking a little bit early. if not any popped/blown primers, then it's not overly overgassed. since you don't have an agb, get 1 or get a little more weight in the buffer.

i added way more info than needed as not knowing ejection direction. what ammo are you using.........should've asked that in the start? i have multiple 6.5creeds in the ar platform and with several barrel mfgrs along with 3 different gas lengths. not 1 of them use a h1 or heavier.


awaiting on more info........................................................

 

[Zen Archery]

But how's it shooting? If it's accurate, ejecting, and cycling next round. I'd run with it.

 

[Shankedit]

if it's ejecting at 1-2:30 it's because of being overgassed. seeing you have aero receivers you should've stayed with their barrels. i speak from experience that their 6.5creed barrel w/standard rifle length gas system is perfect! on my 22" i don't even use an agb and/or an h1-h2 buffer. no brass issues or ejection marks. seams to be unlocking a little bit early. if not any popped/blown primers, then it's not overly overgassed. since you don't have an agb, get 1 or get a little more weight in the buffer.

i added way more info than needed as not knowing ejection direction. what ammo are you using.........should've asked that in the start? i have multiple 6.5creeds in the ar platform and with several barrel mfgrs along with 3 different gas lengths. not 1 of them use a h1 or heavier.


awaiting on more info........................................................

What other info are you needing? I listed the ammo and the direction the brass ejects in the original post.

 

[Shankedit]

But how's it shooting? If it's accurate, ejecting, and cycling next round. I'd run with it.

Shoots really well and functions without any problems at all.

 

[FireFlyFishing]

Suppressed?

 

[Shankedit]

Suppressed?

No not suppressed.

 

[Jamie]

Does your brass look like on it's first firing? How many firings on those? Do you anneal? Are the necks work hardened and not expanding to seal the chamber?

 

[cohunt]

You are getting some weird color lines on your reloads too, are you using flinstones vitamins as powder ?

Maybe try annealing a few of the necks but otherwise I wouldn't be too worried- might just be a "dirty " powder for an ar

 

[FireFlyFishing]

That's way less dirty than my ar suppressed.

 

[Shankedit]

You are getting some weird color lines on your reloads too, are you using flinstones vitamins as powder ?

Maybe try annealing a few of the necks but otherwise I wouldn't be too worried- might just be a "dirty " powder for an

Just realized I left out the part about the brass. My reloads you see there are virgin Starline brass—expanded, chamfered, and primer pockets uniformed. I do anneal but not on this first firing.

 

[ddman]

Does it wipe off easily? Are you using any kind of lube when you size the new brass? If so are you cleaning after? When you load one of your new reloads can you push the forward assist and make the bolt move? I wouldn't think that you're over gassed by your ejection pattern but I've been wrong before. An adjustable gas block is a requirement for me as well as an adjustable buffer ( i run Odin works in most of mine).

 

[Shankedit]

Does it wipe off easily? Are you using any kind of lube when you size the new brass? If so are you cleaning after? When you load one of your new reloads can you push the forward assist and make the bolt move? I wouldn't think that you're over gassed by your ejection pattern but I've been wrong before. An adjustable gas block is a requirement for me as well as an adjustable buffer ( i run Odin works in most of mine).

Yeah it wipes off pretty easy. I didn't size this brass since it was new, never fired, but maybe I should've? I usually don't full length size new brass but I will do some neck sizing or expanding to straighten things out.
When I do size my brass, I'll run them through a wet tumbler for a bit to get them clean. With my AR brass, I clean them before and after sizing.
I've got a Superlative Arms adjustable block but installed the normal gas block first just to see if I could use it and save the adjustable for a different build, but I'm definitely not opposed to swapping it out.
I didn't notice any movement of the bolt when tapping the forward assist but I'll look for that next time I shoot it. I've put about 300 rounds through it so far and it seems to function just fine. Strips a new round from the magazine regardless of fill and locks back on an empty mag.
Thank you for the reply.

 

[ARlife4me]

What other info are you needing? I listed the ammo and the direction the brass ejects in the original post.

i need to quit reading on my phone and responding the same way.

Yeah it wipes off pretty easy. I didn't size this brass since it was new, never fired, but maybe I should've? I usually don't full length size new brass but I will do some neck sizing or expanding to straighten things out.
When I do size my brass, I'll run them through a wet tumbler for a bit to get them clean. With my AR brass, I clean them before and after sizing.
I've got a Superlative Arms adjustable block but installed the normal gas block first just to see if I could use it and save the adjustable for a different build, but I'm definitely not opposed to swapping it out.
I didn't notice any movement of the bolt when tapping the forward assist but I'll look for that next time I shoot it. I've put about 300 rounds through it so far and it seems to function just fine. Strips a new round from the magazine regardless of fill and locks back on an empty mag.
Thank you for the reply.

yes, you should fl size the new brass, especially in ar's! since the gun is ejecting where it needs to be and mag functions correctly on last round then no changes are needed. resize the brass for the fix as factory ammo looks good for an ar.

i haven't had any issues with starline in multiple firearms (ba's, pistol, & ar's).