I took some time today and really gave the barrel the best cleaning I could to get out any possible copper fouling. I used Sweet's 7.62 solvent which is 5% ammonia. Gave it a 5 minute soak, scrubbed it out with a nylon bore brush, then ran dry patches on a jag. The first couple came out a little gray and black, presumably powder fouling. Didn't see any blue or green. Just to be safe, I repeated the 5 minute soak with another shot of the stuff and then scrubbed with a bronze bore brush and ran dry patches. This time they basically just came out clean. Still no blue or green. I don't think copper fouling is affecting my accuracy. Bore looks shiny and clean all the way down. No hint of copper, lead, or other fouling.
While I was cleaning, I decided to see if I had bad mating surfaces between my flash hider and muzzle as detailed in post #73 on this thread. It looks weird to me, but I'm not entirely sure what I'm looking at. I took some pictures so you more experienced folks can take a look. The muzzle end of the barrel does not look smooth or square where it contacts the flash hider, and the inside of the flash hider similarly looks like it has some weird loose chunks of something in it. Doesn't seem right to me, am I crazy here?