Just ordered one for the super lightweight build. Anyone have this set up? Any problems?

My build in progress:
Cavarms MKII lower
14.5"+Phantom ABS Carbon Fiber Barrel Carbine, 5.56 chamber, 1/7
CF FF tube from RB Precision
YHM Front Flip Sight Tower(9394)
ARMS 40L

Tag for results like to see the final weight.
Here's Cal lower colt light weight barrel Hesse carbon upper.

Same with forged alum upper

assembled

I actually just swapped mine over.  For some reason I was having reliability issues with the aluminum upper and the CAV lower. I swapped the Carbon upper and put it on the CAV lower and it runs like a champ (must have been tolerence stacking or something because the aluminum upper runs great on the carbon lower and all other aluminum lowers).

I like the combination and it is very light (sorry don't have pics or an official weight).  My wife has claimed it as her own.

That is pretty cool.  I might just do that with my Cav II

Im guessing it will be under 5 lbs with the iron sights.