What powders are you using in the shorter barrel loads or is that with factory ammo testing?I'm doing an 18.5 right now, it's perceptible less fire ball going from 16.5 to 18.5. My last 300 wsm was 20 inches. My personal opinion is the best length is right in the 18-20 inch range. In our length test we lost only 30ish fps to somewhere in the 19 range, and then 50 or more under down to the specialty pistol length.