6.8spc build

Can't make up my mind on the build...18" would be ideal for me, and me only...The SPCII would be the chamber...

POF upper - 16.5"
LWRC upper - 16.1"
ADDAX Tactical...For some reason their site is down today, but they have side charging handle, and an 18" bbl. Does anyone have experience with their uppers?
Website is up...I dig the side charger...Reminds me of my 2 fals...http://www.adxtactical.com/store/pc/...0&idcategory=0

POF and LWRC are known variables, guys at my club have both, and to me their both the same...

For the lower, would any lower work? Are the dimensions the same?

Mags would be Cmags and or barrett's