Ok, so. for the life of me I cant't figure this thing out. I have a sbr i built a couple years ago that is having only one weird problem. i run it suppressed 1005 of the time and have taken carbine classes with it and it runs flawlessly with every kind of ammo i put through it. From 40 grain vmax to 77 grain 5.56 and steel or brass, 100% flawless, except one thing. The first round of brass ammunition always fails to extract if it sets in there for more than a couple hours. Not the second or any one after that, and not if the round sitting in there is a steel round, but only if the round sitting in there is a brass round of any type. The bolt is making it back and picking up the next round and slamming it into the back of the stuck case.
                       After cleaning the chamber it still does this too. A few times It has almost made it out, but never fully. I put a very thin film of oil on the case sitting in the chamber before I was told this was a really bad idea, but that didn't seem to help either. Since this is a HD gun it has to be able to function properly  and since i dont want the first round I shoot to be a 62 grain herters steel case round this is really becomeing frustrating. Do I need to have the chamber honed? I notice a little discoloration on the brass case after it sits for a long time, and the fired cases do have a little black ring at the base of the neck. Does this have anything to do with it?

I would start with a new extractor and spring.  Run the updated model with the o ring on it for extra grabbing pressure.     If that doesnt work mic the spent cartrige that gets stuck for bulging in the middle. If it is bulged at all.   Chamber issue but I would say extracor is getting weak and when it sets compressed the spring is relaxing and not grabbong at full strength.

Recently, came across some gas keys, where the gas port hole wasn't lining up with the gas hole on the carrier.

Making the whole rifle, undergassed and not extracting.

Check other things first....also, make sure your gas rings gaps are not lined up and at 180 degrees from the next one.

Gas rings are new and at different positions and extractor is an extra power extractor. Also, it runs fine 100% of the time. It's just that first round if it sits too long, and only if it's brass. I'll mic the next spent case out today, but I would think if it were any of these were the culprits I'd see reliability issues on round two and beyond.

^NOT this......why does this persist?

If the extractor is pulling off the rim, then I'm guessing chamber/ammo/extractor......

Ok, it did it again today so I mic the spent case and all is good. Then I cleaned the heck out of the chamber, cleaned it dry and then gave it a little polishing. Cleaned out the chamber again, ran some oily patches through it and then dry until it was coming out white. I loaded it up again with some 223 PMC 55 grain so I guess I'll see tomorrow after it sits all night.

Have you tried firing it after a night sitting?  What does it do under operating conditions rather than setting by your bedstead all night.  Does the recoil against the bolt engage the extractor?
It really is an extractor function issue.
I'm interested in how this plays out and hope you post back.

Tried it again today after sitting for about 20hours with a brass round in it and it failed again. This time it extracted but ejector didn't kick it out. The mouth of the spent case jammed against the charging handle on the inside. Every round afterwards, as always, functioned flawlessly. I'm going to try to change out the extractor and ejector just for the heck of it and let it sit overnight again. This is really driving me nuts!

Did the same thing after changeing out extractor and ejector. Sat for about 20 hours and failed to eject. At least since I cleaned and polished the chamber it fully extracts now. Every round after the first functioned perfectly and spat the brass in a nice consistant pile at about 2:30. I'm running an H2 buffer and a gemtech adjustable carrier. Would the suppressors effect on back pressure be different from the first round considering its full of ambient air instead of hot gas?

Have to warn I have no experience at all with such failure. So, consider my post just as an oppinion from someone that is following with interest your topic.
But I can imagine buffer is somehow stuck. If you load your empty gun you free the buffer manually. But if it stays with a round chambered, the first cicle is not fully completed because of a kind of failure tu push buffer back.

OP, is that first round always from a full mag?  Try it with only 5 rounds in the mag.

Well, two mornings in a row now I have had success. After changing the extractor spring, ejector spring, and cleaning and polishing the chamber I still had failures only on the first round.  After switching the gas setting on the gemtec carrier to unsuppressed it now works fine. This only leads me to think ambient air has something to do with the back pressure. The ejection pattern is at 2:00, a little far forward for me, but I can deal with it. I might try an H or standard buffer to decrease lock time so the suppressed/unsuppressed settings are a little more accurate.

This makes absolutely no logical sense right now why this should make any difference at all.  But I will ponder upon it.  I am just glad it seems to be working out for you.  Thank you for sharing your experience with us.

OP try a different mag.  Also try only loading your mag halfway.

I suspect that you are malfing on the first round because the next round is dragging too much on the carrier, because it is binding in the mag.   Upping the gas helped overcome that additional drag.

Check the mag.