I am just trying out a Primary Arms (PA) 1-6X scope on a 338 fed AR10 and its pretty nice. It does not have a conventional retical.
Whenever they get a new supply in they sell out in a day so you have to get on their watch list and jump on it.
PA 1-4x is nice too.

Not sure if they will stand the recoil, otherwise a leupold.
I had a Leupold 2-7x on mine.

The 375 Ruger has good long distance trajectory with the right bullet.