not sure what its called.(pic is below)
jus for FYI to anyone. i bought a mapgul grip. to make it fit i had to drill into it or cut the nub....i cut the trigger nub thing off, flush with the clam plates when the hammer is cocked back. and it works 100% still.
i watched a youtube video on how to take the whole trigger assembly apart for a DYI trigger job and i can see where it would pay off to keep that nub on. but its only a spring follower it seems.

but yes. after cut. it works 100% still