Gino,
Sorry to hear about the shoulders.. Have you tried the Winchester Feather Lights.. I use those for cowboy shoots and they are substantially lighter than the Winchester AA trap loads. They will NOT function any sort of auto. I have only found em in #8 shot which is just fine for what I am doing but these might be an easier to find alternative. Payin about $5.00 a box around these parts for them now.
They are NOT the ultra light loads they actually say feather light on the box in real small letters and have a gold feather on the box.
Just a thought...
DonT