Hey guys, I am essentialy in the same spot, and as I review what knowledge you all put out I was wondering if anyone knows if I can use either the fixed moe carbine stock or the moe fixed rifle stock by just unpinning the one that came with the sport or if it's absolutely necessary to change the tube no matter what. Im super anxious about messing with the tube as so many ppl report difficult times using the tools available with m&p models not working with castle nut. Thanks