As for loads, I just got done doing some spring turkey patterning with said browning, and the clear winner was the Federal Flight Control load. I tested alot of different loads, inclufing winchester, remington, non-fc federal, and even Hevi-13, and the FC Federal took the prize.
A friend of mine who shoots an 11/87 had the same or similiar results to what you had. He has since sold the gun and didn't remember what choke tube he had used. Local Dealer is trying to sell me Undertaker brand choke tube(High Density) model . My semi-auto has 3" chamber.