Ask these 2 OG'ers. they have done it. I'm assuming it is the civilian Magpul CTR stock along with the RAP4 metal buffer tube. (can someone verify this)

Rx78gp02: My new A5 ARMS SIR mod

Panda86: Panda86's new Tactical and CADPAT SP-1

and here's a similar thread discussing another Magpul style stock: Milsig Magpul M93B Stock?

hope this helps.

__________________