Those are good targets, Phil. I use a globe front sight sized so that I can barely see a little bit of light all the way around the bull at the given distance. The slightest variation in my hold causes part of that light around the bull to vanish. Only when the sight picture is perfect do I see a halo of light all the way around. The thing that makes magnified optics preferable for many is that they allow a shooter to more easily see a disturbance to the sight picture during the trigger press. This allows the same with zero parallax or other optical distortion. It can also be a great training aid. Once you have the bull centered in the globe, relax. If the sight picture shifts, you could have more bone support. Only when you can relax without shifting the sight picture do you have maximum bone support. This is where one can really fine tune his sling technique. Good shooting!