PSA upper might be a deal after all

[FLshooter]

FLshooter - Blue, Green, Red. All three, never noticed a difference. I grease the upper prior to installing the bedded barrel, it makes taking it off less stressful but still accomplishes the goal. Here's something you should do. Get some accuracy data from your builds. Then, break them down, bed the barrels, and re-shoot. It may not make much difference, but I can tell you from personal experience, a squared receiver and bedded barrel are more accurate than not doing those two things. In the end it may well be that squaring the receiver is what does it, but the barrel being bedded and cured makes the union MUCH more solid than otherwise, and in the interest of long term reliably repeatable accuracy, solid unmovable union in this area is a no brainer. It adds 8 hours to your build, with the benefit of a nearly monolithic structure between barrel and upper.

I torque to 42 ft-lbs.

I agree w/you that squaring the face of the upper receiver with a lapping tool is 100% necessary. I’ve been doing that for a long time. And it’s been proven to help with accuracy. I have several gun club acquaintances that swear by bedding their AR barrel w/loctite. It’s just that no one can offer me any proof that actually does anything for accuracy.
And one of the main reasons I don’t want to do it is because I have tried to remove an AR barrel that was bedded. Not fun. Almost makes the upper disposable.I torque my barrel nut somewhere between 40 to 50 pounds.