We sell most bases and rings currently available but our choice in most circumstances are the Leupold two piece standard mount (front dovetail...rear windage adjustable). We find the that a little extra care is required in mounting this type of system in order to get the rings lined up and level but we lap all of our steel rings to ensure proper fit. One piece bases may offer more rigitity between the rings but to be honest I don't think most modern rifle actions require any additional rigidity across the ejection port. Also with Leupold bases you only use three of the available bases screw holes while the two piece system uses all four. A last point to consider is that with the one piece bases there is a little less room to load your rounds from the top as the bar that connects the two bases willl interfere a little with loading. With the 50mm VX-L you should be able to use low rings. Phil.