This is my third post on a problem 16" upper I have.
(First posted in troubleshooting forum)
-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 overfunction, esp the broken rims. That's proof the extractor is working. Has the HS been checked? Pull the FSB off and mic the gas port. A fouled gas tube, or a gas tube with an undersized OD, will cause shortstrokes, as will a misaligned gas port/gas tube. If the gas port is oversize you can bush the gas port and redrill it. What make of barrel/upper unit? On the bent firing pin retaining pin Q, that's in the FAQ II[url=http://ar15.com/forums/announcement.html?b=3&f=66&id=185] here[/url].