I've been working on a load for My 280 AI and have been getting good groups with the exception of a flier here and there. I called Jarrett Rifle and they told me to take my best loads and try different brand primers. They say it can make a big difference sometimes.
For example. 7mm mag 120 TTSX N560 Fed 215M 3550 fps. No pressure signs. Kept everything the same and switched to WLRM working load up to same powder charge and got 50 fps. more velocity and major pressure signs. Then tested CCIBR2 and velocities were close to 215M with no pressure signs. You never know. Test every load over when changing any component. Bullets included.
It's interesting watching the chrony results when shooting the same powder and bullet load but using different primers.
In the .223rem case I get a higher velocity with Wolf small rifle magnum primers compared to the others (Fed 205M, CCI BR4 and Rem 7 1/2). Wolf primers show great promise and are readily available at Powder Valley or Brunos.