I also use a BSS occasionally. Came with 26 inch barrels and both modified choke in each tube. I use 3" BB shells and no issue. However I find the BSS a clunky gun and unbalanced. My go to gun is an older Browning Citori Lighting with a straight grip. It also has 26" barrels with fixed chokes so I had to get the full choke opened to modified. I did put a mercury recoil reducer in the butt. I've been using for about 20 years and have shot well over 10,000 shells in it almost all 3" BB. Seems to me I also glass bed the butt stock when I first got it.
I started out with a 26" BSS, too, for ducks. But, soon found that I liked the 30" much better. Whoever is in a blind with me likes long barrels better than short ones, too. I have never found the BSS guns to be clunky or unbalanced, but we each have our own preferences. They don't handle like a 6# English game gun, but I'm glad they don't. I shoot much better with a gun that is somewhat weight forward. My 30" BSS is also my go to sporting clays comp gun, if vintage guns are not required.
Mine handles plenty lively enough to catch woodies screaming into a hole in the predawn moments. That, and teal, are the ultimate test of handling for duck guns, for me. I went three for three with it last hunt. Also used it for blue wings back during the teal season to good effect.
SRH
