What's the optimum barrel length for a 5.56 SBR? I was considering a 12.5" but finding 11" or even 10" free float hand guards has been difficult. I would rather not use a blast forwarding device. Can I run a 12.5" barrel on a 12" rail with a vg6 gamma ex? Or am I better served going with a 11.5" barrel and 9" rail.