The old Steel Redfield JR one piece mounts and the Steel Leupold One piece mounts always came with one rear screw hole. , I never understood exactly why. Mounted several when I worked in a gun shop. I have had three of these bases on hunting rifles. Never had a problem . One at a Time I changed them out to Steel Dual Dove Tail 2 piece mounts. They are strong and secure with no possibility of windage shifting. If I ever had a heavy magnum caliber, with severe recoil, I would seek out a Custom One Piece Steel base with four screws instead of three, and also Increase the screw size, and re drill and tap the receiver to accept the Larger Diameter Screws. Just as an aside , the most beautiful metal work I ever saw was a Magnum Length Griffin and Howe Mauser Action, with a One Piece Base welded to the action. It was blended so beautifully that it looked like it was all machined from one block of steel. It was in the white with a High Polish. It was simply perfect and left a life time impression on me. It may be difficult now to find a Gun smith, that can machine the custom Base to perfectly blend with the action , and can also weld to that High degree of precession and finesse.