I am setting up my custom 308 for F-Class shooting here at Quantico MCB. I don't have the funds to get a custom made one piece 20moa base. So I am using the Burris posi align rings to start. I have the set of ring inserts that comes with +-5, +-10, +-20. If I wanted 25 moa of adjustment (Roughly) would I put the -20 on the front bottom +20 on top front then +5 bottom rear -5 top rear or would I do it just the opposite. Picture of rifle.