Ok i am trying to built me a new upper what upper receiver you guys recommend for a precision rig. I will use a 20" SDM-R barrel. I am going for a flat top no M4 ramps.
Seeing as your in the Netherlands it may come down to what upper you can get out of the US. A lot of the manufacturers aren't registered with US State dept so can't be exported. I built up a Mk12Mod1 clone on a High Standard upper (its got m4 feed ramps though)earlier this year with most of the parts sourced from Brownells. 18" Barrel was locally made by tru-flite. Still working up loads but so far best load is grouping around 8.5mm (0.33")@ 100 with 77gr MK's, sorry for the side track.
Also had a DMPS lo pro upper. Fair bit heavier but should also make a good base for a accurate upper.