Re: help...rifle build
For me personally you leave the light weight range as soon as you get to a #5 contour, anything under that would be a good choice. This of coarse depends on stock, optics, and accessory choices.
If you're looking to keep things light any weight reduction options help, this includes fluting so I wouldn't hesitste for one second to get it done.
Ignorance can be treated with education, sadly there is no cure for stupidity.