What mount is needed to give proper eye relief on an AR15 with a 10X Super Sniper? I'm building a 24" 6.5mm Grendel and have seen pics of guys using regular mounts, which put the ocular past the rear of the reciever, Larue SPR mounts, and even the Larue extra-extended, but who knows if these guys know what they're doing. Which would work best?