one or both

I keep them both open. Carried over the advice from my archery days. It does make sense that closing one eye would cause muscle tension.

If you have two good eyes it is always best to use both of them for both peripheral and depth of field vision. However, it is almost impossible to shoot a scope with both eyes open when the scope is not in front of the dominate eye. I shoot a scope right handed but since I am left eye dominate I place a small piece of scotch tape on the left lens of my glasses in just the right spot to block the point of aim. This allows the brain to push the dominance to the right eye since the left eye can't see the target clearly. I agree, closing one eye and sighting with a scope never feels the same time after time and both eyes open is definitely more relaxed.

Yeah, closing one eye is the TV (television) way of shooting !

Learn to keep both eyes open. Difficult sometimes, but it's worth the practice.

Mike

Both eyes open for me. Trying to teach my grandsons to shoot that way to. They are getting there.

Well, yes, both eyes but I start with dominant eye to get cross hairs on target then open other eye. I am used to shooting both eyes open from powder burner pistol.