The barrel nut is steel and there are (6) set screws that hold the tube. No indexing problems with the barrel nut. You'll need a 1/4 pin type spanner wrench with a swivel head. Tightening the set screws is a bit tricky the first time, but not really difficult. They are threaded into aluminum, so don't overtighten. Make sure the front screws are centered in the groove in the barrel nut. Seems sturdy enough for a varmint rifle or for sling use in HP rifle. I am quite satisfied with mine.