I built mine with a 24" bull barrel j&tdistributing kit. Out of the box accurracy while sighting it in with Hornady 123gr A-max was 0.81" .
Sadly, J&T has stopped selling them recently. Apparently there are some cycling issues they told me. I'm in the market for another kit, a shorter-barreled hunter, but J&T is not currently a supplier.
Other sites are making warnings not to shoot cheap foreign ammo (I assume they mean Wolf) because of over pressure issues.
Right now, the only suppliers marketing a 6.5mm upper I see are Alexander Arms and Hardened Arms, with Model1sales and the "6.5 Sporter". RedXArms is advertising their 6.5 Grendel is "coming soon", but you know how often that's abused.
Seems to me that commercial interest is waning somewhat, which I consider a real shame, because I think that 6.5 is fantastic. If I can't get a 20" Grendel, I would settle for a 6.8, but it's decidedly second-best for me.