If a .5 variance is insignificant, answer me this. Folks often post ladder test results here and see appreciable differences within a .5g range. What gives?
A long time ago in a far away land, Kenny Jarrett told me not to think twice about +/- 0.5 in a .280AI.
Battue, I have noted that cartridges that are loaded to "higher powder operating pressures" are effected less concerning velocity when powder is added or taken away. Your mileage may vary but IME both the 280 AI and the 270 that have a high Sammi pressure rating benifit from this from what I have seen.
It doesn't surprise me that Kenny specifically mentioned the 280 AI due to its 65,000 Sammi pressure especially if he was comparing notes to a standard 280 that is much lower
It is for this reason that I have come to appreciate loads where accuracy is achieved at pressure! I'm also quite sure its one reason why bench rest shooters often run what we might consider almost insane pressures
