I have a Steyr Pro Hunter in .300 WM. I have tried a two piece base (Warne) with medium rings and it did not work. The bolt handle touched the scope. I could get the highs but the scope is already so high off the barrel. So i tried some two piece DNZ rings/bases. Same outcome. Bolt handle touched scope. So i ordered a EWG 20 MOA base and its going to work minus only three of the four holes match up. Its three enough? I know the older Leupold one piece mounts only used three screws. The problem is not many people make accessories for the Steyr Prohunter. So you have to get Browning A bolt accessories. The distance between the two aren't the same on a one piece. I installed it last night and torqued down to 25 like they recommended. Seems super tight and good.