I use this one slightly altered to both sight in a rifle and to shoot groups when testing lube's and such. At 50 yards I put the white bull on top of my front site and I want to hit the target about 2" high. I can see it very well.
I use a brilliant orange fingernail polish on the front site. I don't care what anybody thinks about it, not many have ever laughed at me when I attended a match and those that did soon shut up.
Everyday I practice shooting offhand with a wooden flint. But I never sight in or shoot for a serious group offhand, those groups are strictly off a bench rest. My shots always hit the same POI whether it's off the bench or offhand if I do my part. I also never shoot at an animal offhand if i can find a rest of some kind but I don't spend an excessive amount of time looking for one either.