If you are doing an AR style build go with an American defense 1 piece mount with 20moa built in. Like this.
https://www.amazon.com/American-Defense-AD-RECON-20-MOA-STD/dp/B00M34XXPU
https://www.amazon.com/American-Defense-AD-RECON-20-MOA-STD/dp/B00M34XXPU