So for anyone else wondering this in the future...the Comfortech stock (61176) doesn't have the nubs but it came with a "B" shim, "SX/DX" cast change shim and an "A-B" 50/55mm drop lock plate in the box. Once I figured out how this goes together, it mated right up. Definitely like the feel of the Comfortech stock over the pistol grip.