I had been messing around for years with my 20 inch I built and decided to do a budget SPR build. My budget was less than $1000 (including optic) and decided that it need to weigh sub 9 lbs with bi-pod and optic. So this is what I ended up with:
It has an 18 inch 1-8 twist spiral fluted barrel mid length gas system, aluminum micro gas block, a MAS "smooth" Upper with deflector, 15 inch keymod free float hand guard, an older Nikon Prostaff 4-12x40mm bdc scope secured with quad-lock see through rings, a M16 BCG, Houge grip, Magpul MOE fixed Carbine stock, RRA Match Varmint Trigger, and my old DPMS lower.
It has not gone to the range yet but will update when I sight and break it in.