Medium or Low rings with this setup????

[Dom]

Fabs has real good points there on what to consider. The only thing I'll add is that if the weapon has iron sights and you use the low mounts, you might just have to remove the rear sight, or at least part of it. Generally you're better off mounting the scope as low as possible. You might want to try the lowest set up, and if it doesn't work, return for a medium set up, Waidmannsheil, Dom.