Why do some prefer the 14.5" length with a permenant attached FS versus 16"? I know authentic military is 14.5, maybe that is enough reason; however, you must have 1x7 twist with a 14.5" barrel correct? That means your barrel will burn out faster. If you do not plan to shoot tracer rounds, isnt 1x9 better overall? Please do not get me wrong, I know the "Cool Factor" of authentic military. I want to purchase an M4 setup and already purchased the 16" setup and wondered if I should get two identical or go with a 14.5 setup for the second rifle. I have two rifles (can't leave my girlfriend out) and I already own an M1A for long distance. Please share your thoughts.