My recommendation is...don't open it up if a dirty gun gets to you!!!I have a bit more time to think and write now Cold296.
I put many thousands of rounds through my sub2k in competition. Never once, when fed brass cased ammo*, did it malfunction. Not even with my butterfly fart loads that just made minor power factor. I stopped using it because of my incompatibility with the inability to easily get into the innards to make sure everything was clean. I could never quite come to grips with the fact that even though I couldn't see that it was clean that it was functioning just fine. So now it's a afe queen. But it's so reliable that if the zombies were to come out of their graves it would be high on my list of SHTF firearms.
*Mine is a jammamatic with aluminum cased ammo. It's the only sub2k I ever heard of that doesn't like aluminum cases. Lucky me, right?
Mine was filthy inside when I installed some MCarbo parts!!! Places that could have only gotten filthy from the manufacturing process. Unless you have an ultrasonic cleaner big enough to handle the whole gun you're either going to have to tear it down to get the gunk out or simply live with it. Consider it a test of mind over matter!!!
I normally remove the bolt and run a lint-free rag thru everything I can to remove what I can't get with a snake or a brush dipped in cleaner.