ALL TESTING WAS DONE WITH THE SAME BARREL PROGRESSIVELY SHORTENED FOR NO BARREL TO BARREL VARIATION AND ALL AMMO FOR EACH LOAD FROM THE SAME LOT. ALSO ALL SHOOTING WAS DONE DURING A 5 HOUR PERIOD ON THE SAME DAY USING A LABRADAR TO MINIMIZE THE EFFECT OF ATMOSPHERIC CONDITIONS. ALL CHRONOGRAPH STRINGS WERE 10 SHOTS WITH THE HIGH AND LOW SHOT REMOVED FOR AN AVERAGE OF THE REMAINING 8 SHOTS.
AS YOU CAN SEE AS THE BULLET WEIGHT WENT UP BARREL LENGTH HAD LESS EFFECT ON VELOCITY. AVERAGING THE 16.25 TO 20 NUMBERS IT WORKS OUT TO 10.5 FPS PER INCH.
not sure how they addressed the gas tube length as the barrell was progressively shortened.