I need some help here gun gurus?

A Springfield M-1A would be a good choice. That's a .308 caliber. If you could find a semi-auto copy of a Browning M1918 BAR, that would be pure awesomeness, chambered in .30-06. I don't know, offhand , of any semi-auto "tactical" rifles in any of the .338 calibers (Win Mag, Lapua, or Norma). I could be wrong, it's not unprecedented.