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

[Stevo]

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.

I'm just going by what you posted here:

As far as front band fit, it needs to make no contact on it's rear face with the front of the stock. It also needs to have ~3-5 lbs tension between the lip and the bottom of the stock and be well centered. The handguard should not touch the stock. The triggerguard should take some force to close. There's lots more, but those are good starting points.