I'm a big fan of the "tactical" style rail and rings for a precision rifle. Look at those by Seekins Precision or Badger Ordnance. I'll admit that Glen Seekins is a friend of mine, but he does build a great base & ring combo that will get you that 20 MOA if you want it. Seekins builds from high-quality aluminum.
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Also have two rifles set up with Badger bases, one flat, the other a 20 MOA base. I simply can't fault Badger. Very high quality.
Regards, Guy