In my 11-87 I found the Win. Supreem Double x Magnum #6 - three inch worked the best.
I went to a Turkey Gun Patterning Event at a Shooting club Three years ago. They had about 25 different loads for me to try at $1 a shot. It was well worth it .I shot about 10-12 different shells and realized I had found the right one. I shot all the different loads in my gun for $10-$12!
If you can find a event like this in your area that is the way to go.
Roman