Yukon, another thought. You talked about using an indoor range. What distance do you plan to zero your rifle at?
A 50 yard zero for the grendel will have you very close at 100. A 25 yard zero will have you very close at 200.
You should be on paper without issue if you head over to BPR and use a rifle bay at 25 yards (minimum they let you shoot) then if you want zero for close to a hundred run it out to 46 or whatever they have and you'll be in the ball park for going outside.
Here's the 200 yard zero I had posted prior.