I didn't notice this before but now I do. Saturday night I was hog hunting and after I shot 1 and went back to bed, I left 1 in the tube in case they woke me again (I use a motion sensor at the feeder). Sunday morning I emptied the rifle to find this round and know it didn't look like this going in the mag. Is the install of the suppressor cause too much gas to blow back on the new round? Can't be heat related, it went from cold to 1 fire and back to cold.

100% normal. The suppressor adds more gas coming back into the action and makes the chamber and ammo dirtier. You will need to clean more often and keep your BCG lubed up.

Yup.

So much carbon comes back in my suppressed LR-308, that the top three rounds in the mag get pretty dirty. Action and bolt get cleaned and oiled quite regularly. I want it ready for a sounder of hogs. It doesn't take but a few minutes to pull the rear takedown pin, pull the bolt, wipe it and and inside of the action down, and re-oil. Better than the "locked up AR" I am all too familiar with.

Gary,
If you are ejecting 3 to 4 o'clock, your gas amount is perfect. If it is ejecting more forward from you, it is over-gassed.

Thanks for the confirmation gentlemen. It is ejecting a little too forward, maybe 2 o'clock. I'm not gonna fix it unless it breaks.

Every AR needs an adjustable gas block, especially those that are suppressed.

I think over-gassed may cause the bolt to close a little too quick on a still ejecting empty case, and I think being over-gassed is tough on the BCG. Better verify that with Kyle though. He's way more versed in AR's than I am.

So dirty and over gassed are separate issues...

Running an AR over gassed CAN lead to some problems but not always. Some issues include feeding problems, higher wear on parts causing failures, or trouble extracting.

There are a few solutions. You can get an adjustable gas block, change out the buffer to a heavier buffer, down load amno. Or take the risk and run as is.

Yes.

My LR-308 has a 3 to 4 o'clock ejection, and cycles very reliably, so it is not over-gassed. But rounds in the mag, and the BCG get very dirty, very quick.

yep, normal
my favorite GB is the SLR and I am a huge proponent of coated BCGs, they run smoother and cleaner up easier

A buddy of mine had the same issues with running a suppressor with a 6.8. It's not if it breaks but when. Of coarse it broke when we were shooting at pigs. Now, we both shoot 6.8's with .30 cal suppressors, but different manufactures. My runs a little cleaner than his did without the adjustable gas block but not much. So an adjustable gas block will not solve the dirty carbon issue by no means. The adjustable gas block should keep you from breaking a bolt if adjusted correctly. Like the others said, the first few rounds get carbon blow back on them while in the magazine. I clean my AR after I shoot it every time. I pay particular attention to the camber. After firing, I'll always eject the round out of the chamber and lock the bolt open to the rear to allow the chamber to cool as well. Seen a couple guys end up with stuck cases from excessively hot dirty chambers. Keep in mind they don't clean their rifles that often either. They'd shoot 30-50 rounds then leave the round in the chamber till the next time we went to hunt and couldn't get the round out. After a couple times of that, they don't do it anymore.

^^Gospel truth. All of it.

If carbon was blood my 6.8 chamber/action would look like a horrific crime scene. Top 2-3 cartridges are almost black sometimes, soot everywhere. Gas block may not help much but that may be the next step.