That's ~kind of~ how I caught it on the first round? I normally ignore the cannelure, so I don't ever measure it, and after several thousand rounds of it being in the same spot I never even considered they would move it. I set my calipers, bumped the projectile down to the cannelure to set the seating die, pulled it out for a measurement, then made the wtf face. My brain went in to worst case mode though. Did I trim too short, did I buy the wrong bullets, did the projectile slip due to a lack of neck tension, what did I do wrong? So then I started measuring EVERYTHING.
The only thing I really did "wrong" was not set the seating die with a round I knew was set to 2.255". And you best believe there is now a note about the cannelure measurement in my recipe for these bullets.