I would start at about 25 inch pounds on the action screws and not go more than 35 inch pounds unless they are pillar bedded, as far as the barrel band I would try my best to avoid any torque at all on it, I don't see how this could be anything other than detrimental to accuracy. If it were mine and I was looking for the best accuracy I would probably take the barrel band off entirely.

Hope this helps!

Bob