Here's an unmentioned consideration...stock fit. Most understand that shotguns "aim" with stock fit. If you're wanting max speed for snap shooting, stock fit is equally important for a rifle. The ideal is to have the same line of sight for both scope and irons to achieve the same fit when using either. To this end, the scope needs to be low, low...and the irons a bit high to have identical stock fit with either. Most doubles come closest to this ideal with claw mounts. For me, heavy bolt rifles need a super low side mount and an island mounted open set of irons. When you can shoulder your rifle and have the irons align perfectly, then mount the scope, shoulder the rifle and have the scope align perfectly, you've achieved nervana. My 505 has a side mounted G&H solid ring mount with base tig welded to the receiver. The Lyman 2 1/2X Alaskan, a 7/8" tube scope, has identical line of sight to the island mounted NECG irons. The smaller diameter scope without objective bell gets the scope as low as possible.
Otto