Well I'm not sure what has happened. I changed out the rail for another and followed the directions and the torquing and re-torquing to the letter. Function checked fine. When I took it to the range it was off way left. Looking at it the barrel is not centered side to side in the rail. It seems to be angled to the left. When I drop a laser bore sight in the chamber I don't get a nice round dot. It seems to be distorted. I suppose I'm going to pull it all apart this weekend and check everything. Everything was perfectly fine for 8 years prior to changing out the handguard. Is it possible for the barrel to be canted with the barrel nut torqued down?