I think my head is going to explode............(updated, sort of, post 32)

[jmoore]

What does "band tension" refer to?... It also has the 3-5 pounds of tension at the lip on the front band that you mentioned and can be deflected upwards approximately 2 mm before it contacts the handguard.

Ummm...???

As far as freeplay, 2mm ought to do. BUT, it might do to paint or otherwise lightly color the close fit areas to check for rubbing during the firing sequence.