I've found that when I use the thumb break grip with my Magpul MFG (mounted on a Centurion M-Lok fore end) I get a sore, strained feeling from the knuckle on my pinky almost all the way to my elbow. I notice it more after use rather than during; I also notice that it's as bad or worse if I just the MFG as a hand stop. Has anyone else had this? Would the slight angle of the BCM vertical grip help this? Are there any other remedies for this (changing grip techniques, adjusting the stock, moving the grip forward or backward, etc.)?