Not a bad choice in the bunch. I don't own one, but know some that do, and they swear by Schmidt and Bender.
He needs to pick a scope, and read what travel it has available. Half is available on a 0 MOA base.
To convert MOA to Mil, divide MOA by 3.43, and you get the value in Mil. So a 20 MOA base is the same thing as a 5.3 Mil base.
Then he needs to go to a ballistic calculator and find out his worse case scenario environmental conditions elevation correction, for 2000 yards. Once he knows how far up is going to need to dial, he will kknow how much of an elevated base he needs to give the scope more POI up.
I like a Harris bipod better for prone, and an Atlas better for positional/ barricade shooting.
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