Is the u shaped support inside stock 3.5" from receiver for upward pressure on barrel, to keep barrel centered or both? I was planning to relieve that but, didn't know if that could cause barrel to cock to one side of the stock or the other? Thanks!
Being centered is less of a concern than unequal pressure. The action screws will hold you pretty close but you might find it favors one side, but it’s not a concern.