First shot reslted in a failure to extract. New barrel, new B/BC, SP1 upper, gunsmith assembled.
Ammo was Winchester Q3131 circa 1994.
So what happened, rough chamber, short headspace, operator headspace?

From the picture of the brass, it looks like your chamber is rough.  Looks like the brass expanded in the chamber and stuck.  Maybe it's just the picture.

I agree,  looks like a rough chamber.  

Look at the "ring" on the brass in the second pic.

Quoted: From the picture of the brass, it looks like your chamber is rough.  Looks like the brass expanded in the chamber and stuck.  Maybe it's just the picture.

That is what i thought also, the brass is rough on all sides just as in the picture. So how do I go about polishing the chamber?

some ideas emailed

Parrandero, hope you don't mind me piggy backing your thread but I just got my M4 back from JT yesterday and I had a new Wilson chrome lined 16" bbl installed and I had the same problem today with ripping the brass like shown in your pic. It didn't do it for the first 30-60 rds but the next 20 it did almost every round and then the last 30 it did fine. I thought it was my brass which was a mixture of reloads and new winchester white box from wal-mart (go figure), but I have never had this problem until today.

What's the likelyhood of this just being bad brass?