It's been proven over and over and over and over again that light-weight bullets can shoot superbly from fast twist barrels. The 10-shot group pictured below was fired from a Noveske barreled AR-15 with a 1:7" twist using 55 grain bullets.  The group has an extreme spread of 0.74"




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Twist has very little to do with group size vs bullet weight. Almost zero negative impact. This is a gun myth. Higher twist rate allows for larger variation in bullet accuracy due to jacket thickness variation or lack of perfect weight balance due to increased rotational force. The solution? Use bullets with near perfect balance concentricity and keep jacket thickness variation as small as possible... AKA match bullets.