You all must have different A5's and Model 11's than I do. My 12,16, and 20ga Brownings and M11's all have the notch cutout, including my RAS, predecessor to the M11. Even the 1902 made FN Brownings have it, they are missing the MC though.
Powder if you are talking about this screw in front of the bolt release, you are in bad shape. You will probably have to have someone make one for you.