Re: Picatinny Rails?
Near makes a good rail as well as Badger Ord. and Night Force you can't go wrong with any of those.
With any rail when you sit the ring(s) on the rail they will be able to move back and forth in the slot so what you are seeing there is normal.
When I am mounting rings to a rail I get them positioned in the slot I want them, then push the front ring all the way forward in the slot and the back ring all the way to the back of the slot. Doing that will help keep the rings from slipping on the rail.
It is best to use a torque wrench to tighten the rings to the base. It is possible even with quality rings and rail to create distortion or stress by over tightening the rings. Most manufacturers recommend in the range of 60 to 65 in/lbs.
Don't forget a quality set of rings to with that rail...... NF, Badger, Leup MK4....