This is my dilemma. The 6.5 groups so small it should be against the laws of nature. The 5.56 is the exact opposite. Maddening to my rationale. I'm gonna try one of the ammos suggested. If that doesn't work will probably shop for a new barrel first then, I really don't know what to do.^ My MVP had a different barrel. I believe it was a 24” 1:9 twist. The most accurate ammo I shot through it was actually Prvi Partizen 62 gr. Which worked out because it’s a cheaper brand. Never would group like my RPR though.