The part that rotates when you fold the legs has divots in it for legs all the way forward, straight down, and straight back. The back side of the bipod is the side that has the scallop where it connects to the shelf. With the back side back, and legs all the way forward, the pin should retract all the way into the divot as that divot is about twice as deep as the positions all the way back and straight down. Believe I have pics and instructions in the bipod group buy thread.
I have seen where the divots don't line up w/ pins perfectly or are not deep enough... Just take a drill bit and drill the divot slightly deeper or wider, test, touch up w/ blue and you're done...
For shallower divots, I've seen puddle weld fillers when those were apparently drilled too deep at the factory too; point being, much of these surplus items were hand assembled and to very loose tolerances... And if you screw up, you can fix them just like the factory. If I recall, the legs themselves are an alloy while rotating part being discussed here and the actual bayonet lug connection are both steel. Believe feet are steel too, but not 100% offhand.
