I tried putting a strip of scotch tape over my left lens today at the range. It felt awkward looking through them when I wasn't aiming, but my eyes felt very comfortable when shooting. To be honest, the first 10 minutes or 25 or so shots were all grouped at 1 o'clock. They were tighter than usual, but off the bullseye. Very weird! After those, the last 125 or so felt much better. Hopefully sometime in the near future I can take the tape off and still shoot well with both eyes open.