RE: BLURRY PIN ?
OK, I don't have perfect eye sight anymore and my pin is blurry all the time whether I concentrate on the pin or the target. I do concentrate on the target though. I use a very bright fiber (HHA sight) and was having troubles during any daylight hours, the pin giving a starlight effect. What I did was take electrical tape and wrap it around the guard which toned down the pin by leaps and bounds, So now the thing is still blurry (I'm 62), but the starlight is gone and I'm able to aim a whole lot more effectively.
This might not be your problem, but for the price it's certainly worth a try.
You might play around with different size peeps, too. You'd be surprised what a slightly smaller or larger peep will do.