If my memory serves (and it often doesn't) Buehler rings once came with spacers that went in the top. I'm talking way back in the 50's. It was my favorite mount at that time as I liked the rounded top of the ring where the screw went. I thought it looked smoother. I remember the shims as being cut to match the shape of the ring at the top with a hole thru them but don't remember whether you could peel them to different thicknesses. Something in my memory says you could. I also used the Buehler safety on all my Mausers at that time. They made good products.