I have had this experiance when i am shooting my bow. I lowered my peep that helped out a little. also I thought that my eyes just needed to be checked (might not be a bad idea turns out i have an astigmatism in both eyes :shade but last archery season it happend alot when i got "buck Fever" my eyes would blur when i was at full draw and trying to foucs on where my pin should go on the animal. I would just relax and try using your "periferal vison" get your target in sight in the sight of your peep and pin then look at your pin and if its in the general area of where you wana shoot then release. hey and if im wrong for you it was worh a try ....I normally don't shoot rifles without a scope so that comparision won't work. And in theory if the shotgun fits you correctly you should never see the bead, just the duck, clay, pheasant, etc. I've dropped my draw weight by 5 pounds and it has made no difference. It actually feels like some form of eye strain.
What he said. X2It is impossible for the eye to focus on both the pin and the target if there is an appreciable distance between the 2...it's solely a matter of physics. If you are bouncing between both the pin and the target, then you are speaking of a process called accommodation. The older you get the slower this process is...it will also vary with light conditions also.