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.