You would have to ask me that!! I do know that at 54.5 you're looking at a measly 3150 (got to start somewhere), I cannot remember for some reason where the velocity is at 56.5 (Hey, it's Monday) i'll try to get that to you.
You're correct, not the first bbl for me either, next one will be 6-284 also... horse power is addicting! not what a fella would want in a tactical match for sure, but man 'o' man are they flat shootin..
Where I'm at I've been having trouble finding coyotes to cooperate for bullet testing. How many grain bullet were you pushing. Former bbl I was getting just about 4,000 fps with 70 gr Nosler BT and 3600+ with 87gr V-Max both using powders like Re#17,19 and H4350 and that was with a HART 26" 10"twist Looked through it with bore scope and first 6" there was no rifling the rest looked burnt up. That was about any where from 1200 to 1500 rnds.
How does it profit a man if he gains the whole world but loses his soul?