Local gun shop had one, lucky find, they always seem to be my place when I need something specific.
Rail is made by Mako group, I like much better than the vanilla polymer forend that came with it.
Back side went under the delta ring, however did not just pop in, had 4 bolts that clamped the halves together over the ring that held the stock forend.
Bipod is by grippod http://www.grippod.com/
Spring loaded, retracts into the grip, me likey