Been lurking on the forum for awhile and figured it was time to join so I could ask some questions and seek some advise.  
I'm not new to shooting, but it has been awhile.  Most of my experience has been with HK (MP5SD) and Colt (M16A1/A2/M203).  Looking to build a 6.8 or 7.62 CQB (0-300m), and would like input from members more experienced with the clones (aftermarket) than I am.  Right now, I'm leaning toward LMT upper (don't have a clue about which lower) in 6.8 or Armalite if I go 7.62.  Like polygonal rifling (Noveske), and I've read through the debate on folding sites (still don't know).  LW for the gas piston system and it will be probably (90%) have an interal suppressor.
Any and all input welcomed.  Hopefully I haven't opened too large a can of worms with this!