I can say this for certain. I had a hell of a time zeroing a Savage BA 10 rifle in .308 caliber. I have a Nikon Prostaff 5 Scope First focal plane scope, which has a 1" dia. tube. I bought the Leupold 1" diameter steel rings (which can be mounted for either picatinny or Weaver style bases)and mounted them on the rail that came with the Savage rifle. I lapped the rings and secured into the respective base saddles, and mounted my scope correctly. I then used a wheeler green laser bore sight tool and went to the range. To make a long story short I couldn't get my shot placement in one location. After removing the scope and examining the rings I found play on both of the ring bases ( mind that they had been blue lock tight and torqued to 18 pounds ) , so I removed them for examination. To my surprise I found that the screws that attach the bases saddles to the rail were completely round and did not have a flat on them, and because they did not have a flat on that screw ring bases did not fit the weaver style rail.THEY MOVED FROM SIDE TO SIDE JUST ENOUGH TO PREVENT AN ACURATE BULLET PLACEMENT. I replaced them with Weaver Grand Slam steel rings which have a flat on the mounting screw that mates perfectly with the rail. After replacing the rings with the Weaver Grand Slam rings I went back to my range. I used the Wheeler precision laser bore sight tool and proceeded to print respectable 1/2 minute of angle groups at 100 Yds. Moral at least for me is to check those rings out and make absolutely certain that they will attach properly to which ever rail style you choose. Please do not skimp on the rings. STEEL Is the way to get a solid foundation for your scope not aluminum which may flex and shift or otherwise move on you if you are using magnum chambered firearms!