Hornady theory would make sense . About 3-4 years ago I did a test of tipped bullets. I bought a box of every type on the market. Reds ones ,Green ones ,Black ones , White ones .... ( wait that's a song !)... Blue tips and Bronze tips ,Yellow tips. At the faster velocities the pattern opened up. Also the red tipped Hornady's and the Remington Bronze tipped where more accurate than the Noslers's. Had one box of Blue tip Barnes it was in the middle. The 125gr 30cal tipped bullets where not accurate when pushed out of the 300wsm. While the 150gr ,155gr and 168gr were very accurate with the 308.