So...Building a rifle currently. Leaning towards a longer barrel, but there is the possibility of going with a 16. We used to put carbine buffer tubes and collapsible stocks on M16 A2s for short people, before the M4s became prevalent, but something about it never sat right with me. So If I dig up a 20" bbl, should I go with the rifle length buffer tube and stock? Or should I go with the adjustable?