Sd vs barrel length
Yes, I ran a test with a 40-X just two bbl. lengths 26" and 20" not the same bbl. but both 16 twist 6 groove Liljas. Started the test to see what the difference was in velocity and tuning capability for accuracy. All testing was done same day same weather conditions. My chronograph also gives SD so when I printed results from 20 10rnd groups from each bbl. all same Eley match lot code. My results were conflicting to say the least. First off velocity avg. was 9 fps faster with the long bbl. Noise was greater from short bbl. giving the illusion of faster bullets. Long bbl. seemed to show repeatable results tuning with the Harrell tuner, short bbl. seemed inconsistent and results did not repeat as well. The long bbl. showed a marked improvement in Standard deviation with the lot code tested. My results, short bbl. 31sd, long bbl. 24sd. So from the test I ran I would conclude the longer barrels are easier to tune and also give a better SD, all equaling better accuracy, so we would think. Truth is targets don’t lie and the 20” barrel group avg. was better than the 26” bbl group avg. I chalk it up as a better barrel, but one would still think better SD and easier tuning would be the way to go. JMO
