Thanks for all of the replies, I think that is what is stopping the barrel nut from moving more, the gas tube. I've never had any problems with this upper so I think I'm not going to worry about it until I can link up with some ARFCOMers with the knowledge and tools to take care of it.
Thanks for the offer Forest, if I lived in MD I'd definitely take you up on it.
The dirt bike I'm selling is a 1979 Suzuki PE175, it's a 2 stroke bike. In running condition. The clutch cable needs a little stop on the end. Other then that the bike is great. These are bulletproof bikes which you'll see if you do any kind of research. The plastic on this bike looks nice and has a brand new fender on the back. Comes with a Vega helmet that is almost new condition, and a set of Oakley goggles (scratch free). Oh did I mention it also comes with an almost complete second parts bike that is simply disassembled. All of this for a mere 500 dollars [;)]
If you're in Ohio we may be able to arrange something for delivery as well.
Come on it's going towards a new upper [:D]