For those of you who have mounted metal rails / handguards on your rifles, have you noticed anything in terms of flex at the point of connection? I have the Troy 13" TRX Standard (mentioned above) on my 5.56 AR, and it's certainly not light. I'd love to do something like this to my 15-22, but am concerned that the extra weight would pull or stress the upper receiver a little too much. Any thoughts?