I have a 870 Wingmaster with a 2 3/4 chamber made before they started putting recoil pads on everything. I know some of the 3 inch barrels will work as long as you use 2 3/4 shells. But, will they all interchange? Seems like some are marked LW or such. And, does the long chamber mess up the pattern since the forcing cone is further out if using 2 3/4 shells?