Are the Featherweights the same as the Winchester Lites? The Lites use a 26 gm shot charge and Winchester WAALite powder.
I was looking for a low velocity, low pressure load to use in my L.C. Smith guns and had seen these shells in stores. I had plenty of the newer Winchester AA hulls, and went to the Hodgdon site and found the receipe for the factory load. Made a bunch up and tried them. The first time I tried them was on a cold spring day and had some bloopers. This was using 11.8 grs of WAALite powder (my Mec bushing #18 averages this), WAA12SL wad, Win. 209 primer, 26 gm.(under 15/16 oz. shot, with a 302 1 oz bar)and AA hull. Produces 960 fps, and 5600 psi.
I did increase the powder charge to 13.0 grs and it helped.