Here is my data from my AR-15 rifle set up as a MK-12 clone....18" barrel with 1:8 twist. Data from an elevation of 3900', temp at 70 deg F, humidity at 18%, pressure at 29.94. LC brass trimmed to 1.750" and CCI 41 primers. Using 77 gr SMK and a COAL of 2.260". My most accurate load is 25.6 gr...