I talked to a man yesterday who builds rifles that he guarantees will shoot under 1/2" groups at 100 yards. I asked him what kind of rings and bases he uses. He said he uses steel Weaver Grand Slam bases with Burris Signature rings with incerts. Sometimes he uses Ferrel bases. He said the Leupold turn in front bases with windage adjustable rear bases are under tension and aren't as accurate as the Weaver style slotted bases for clamp on rings. What set up do those of you who shoot long range or for competition use? What rings and bases do the best job of securing a scope even under heavy recoil (.338 and up)?