I do use loctite to bed the barrel into the receiver, forgot about that.
UP, I didn't forget about the trigger, that was in the section of everything thing else is for you. A good trigger does nothing for the mechanical accuracy of the gun. It just makes it easier for us to shoot it.
As for squaring the bolt, I'm not smart enough to figure out how to measure it but I have a friend that had a gun that was just almost a great shooter. One of his customers and friends is a top shooter/Smith and he looked at it. He lapped the bolt into the barrel extension and viola, the gun came around. Ever since then I've played with bolts when everything else was done.
Another thing is don't over tighten muzzle devices. I use red or green loctite and get em timed by trimming the crush washer and count on a barely snug fit and the loctite to hold it.
Great suggestions on not over torquing the muzzle device. I've been playing with those recently. I was also on the net checking out different reaction rods for barrel nut and handguard and muzzle device R&R. I saw where one guy said they can damage your upper receiver, if you over torque the barrel nut or they can actually damage the upper if you have a barrel nut that doesn't want to come off. I guess the index pin and the receiver take most of the load when using the reaction rod. Some may say bs, but it is true. For that reason, I like the looks of this Midwest industries rod better, as it will use the charging handle groove for extra added strength. It also ensures your barrel gets aligned perfectly with the receiver and the bolt. Check this out:
