RE: 20 yard mental barrier
vision
Your vision probably doesn't allow you to PICK the exact spot you want to hit. Thus your focus is lost.
Do me this ..... tonight put a quarter size white or bright yellow spot on you target. Step to 20 yards or 25 yards.
I'd be shocked if you don't group tight. Why ? You now have something to focus on, a bright spot todraw you to.
try it