This is my third post on a problem 16" upper I have.

-bought it used
-problems regardless of ammo
-ejection problem, will not throw cases out very far
-rims are sometimes broken off of cases (once every 2 mags regardless of ammo)
-I polished the chamber with scotch brite
-Test fired again this weekend, but still same results. *plus* one gas ring broken, and firing pin retaining pin bent.

I am thinking too much pressure feeding into carrier.  This is causing bolt to try and extract too early, etc...

Could this be from too large of gas port in the barrel?

Could the gas tube itself have problems with corrosion on the inside or other things whuch could cause overpressure?  It looks like an old gas tube.

Would an adjustable gas tube fix the problem?

Sounds like the gas port is too large - an adjustable tube would baind-aid that problem.  If you want a definitive answer post this in the Troubleshooting fourm.  You won't get alot of responses but you will get the correct one - Tweak is the moderator over there and he knows his rifles.

I'm far from being an expert, but it sounds as though it may be overfunction.  Go to the troubleshooting forum, read the primer at the top, and post your problem.