Just spit balling and bored but in a 16" muddy 556 gun what is the desired gas port size. I know there could be a lot of variables.. Let's say no suppressor and like xm 556 ammo

Also mid length is the norm it seems like..but why not more intermediate length 16" barrels?

Int. length I'm assuming you would want a adj. gas block

I'm bouncing ideas for finishing up an upper.