my fn-49 is the 8mm egyptian version and it is pinned, but that is how i recieved it. it is pinned to the rh side of the mag groove on the trigger end of the mag/box. if i was going to do it myself i would consider using the method marstar uses on the sks. basically its a metal block epoxied into the bottom of the mag. if you do it that way make sure the spring can move freely.