DUDE! Had another cup of coffee and thought about this again. This is why I was having so much trouble tuning my bow!
A bit of history: Frustrated with the marginal performance I've had for the past year out of my proshop "tuned" bow, I began tuning my own bow a month or two ago with
@Gamover06 's help. He urged me to go to a lower deflection but I wanted to stick with my current Carbon Express Maxima BLU RZ 250 arrows (yes, actually a .400 spine) because I had so many of them and they seem to be within spine spec for DL/DW (based on Carbon Express' spec calculations). I added 300gr to the front of them and was COMPLETELY BAFFLED as to why they were showing symptoms of being over-spined according to Easton's guide (thanks
@Weldabeast). I eventually gave up on the Carbon Express' altogether and began testing with the .350s I mentioned above and had great results with that same 300gr up front. It was really confusing that the .350s tuned when the .400s showed over-spined.
…… the RZ 250s cut at 26 1/8" weren't really a .400 spine!