I have a 2007. Great trigger and reliable, but the gas cylinder was out of alignment, so when I had the barrel chopped it had to go in order to mount a gas lock front sight properly.
Also, now that I look at the new threads they seem off to one side, but lined up with the bore. It would seem that the bore is not exactly center in the barrel. I didn't even know this was possible. Indexing is a hair out and rear sights won't come off.